Chapter 3. Endoscopy and Endoscopic Intervention

Over the past several decades, flexible endoscopy has shifted the management of numerous gastrointestinal diseases from the surgeon to the endoscopist. What had started as a diagnostic discipline has now become one of advanced therapeutic potential. The concept of performing endoscopic surgery has become a reality with the advancement of endoluminal therapies for neoplasia, gastroesophageal reflux, and obesity. In addition, with the significant investigation into natural orifice translumenal endoscopic surgery (NOTES) and the development of advanced endoscopic tools, the ability to perform intraperitoneal therapies without abdominal scars continues to become more possible. This chapter will address the indications and techniques for upper and lower flexible endoscopy as well as the recent advances in imaging and interventional endoscopy.

Imaging

The flexible endoscope was initially developed in 1957 as an imaging device dependent on the delivery of light and transmission of the image along multiple bundles of chemically treated glass fibers. The fiberoptic bundle is 2–3 mm wide and is composed of 20,000–40,000 individual fine glass fibers, each approximately 10 μm in diameter.1 The image undergoes a series of internal reflections within each fiber, which are coated with low optical density glass to prevent escape of light, as it is transmitted up the bundle. Due to formation of the fibers and surrounding material, a characteristic meshed image is seen in fiberoptic endoscopes, which inherently results in a lower resolution than that seen with rigid lens systems. In addition, if the fibers become cracked, the image is not generated at this site of the bundle and multiple black spots are seen.

When utilizing a fiberoptic endoscope, the endoscopist views the image through the eyepiece at the instrument head, or alternatively, a video camera can be affixed to the eyepiece to transmit the image to a video monitor. The progression from fiberoptic scopes to the videoendoscopes, we use today, has allowed for advancements in our ability to perform more involved therapies, educate physicians and endoscopic assistants, and obtain static and dynamic recorded data images for improved clinical management.

The majority of endoscopes in use today are videoscopic, although in many parts of the world, fiberoptic systems are still the standard. In these videoscopic systems, the visualized image is created from reflections onto a charge coupled device (CCD), which is a chip mounted at the end of the endoscope rather than via the fiberoptic bundles. The CCD chip has thousands of pixels (light-sensitive points), which directly increase image resolution.2

Imaging Advances

There have been many recent advances in endoscopic imaging techniques. The purpose of most of these techniques is early detection of dysplasia, which might elude standard endoscopic visualization. Clinical use of new imaging is limited principally to specialized centers, but future widespread application of an imaging method for early dysplasia detection is a certainty.

Chromoendoscopy

The aim of chromoendoscopy is to detect subtle mucosal abnormalities. Commonly used agents include Lugol's solution, methylene blue, indigo carmine, and Congo red. A 2–3% solution of potassium iodide (Lugol's solution) reacts with glycogen in keratinized squamous epithelium. Normal squamous epithelium stains a deep brown, but inflammation, dysplasia, and carcinoma do not stain because of a lack of glycogen. Lugol's solution has been shown to be effective in detecting Barrett's esophagus as well as screening for squamous cell carcinoma of the esophagus.3

Magnification Endoscopy

In magnification endoscopy, a cap with a magnifying lens is fitted to the tip of an endoscope. The mucosa in contact with the lens is magnified without impairing the maneuverability of the scope. Degrees of magnification range from 1.5× to 115× and can be changed on the scope by turning a dial at the hand controls. The technique of magnification endoscopy is frequently used in conjunction with chromoendoscopy. Chromoendoscopy is used for broad surveillance of the mucosa followed by focused examination of suspicious lesions in magnification mode. This combined examination has been reported in case series to enhance detection of Barrett's esophagus, chronic gastritis, Helicobacter pylori infection, gastric dysplasia, and early gastric cancer.4–6

Confocal Fluorescence Microendoscopy

Standard endoscopy uses white light to visualize a large surface area with relatively low resolution. In contrast, confocal endoscopy aims to visualize the mucosa and submucosa with subcellular resolution, a technique deemed optical biopsy. The process of confocal magnification reduces out-of-focus light from above and below the focal plane at a magnification of 1000×. The system is designed to measure tissue fluorescence; therefore, an exogenous fluorophore (a molecule that causes another molecule to be fluorescent) is usually administered. Varying depths of tissue are examined by altering the focal plane, and images from different depths are stacked together to create an optical slice of tissue, thus the term optical biopsy.4

Narrow Band Imaging

Most endoscopes now have the ability to switch from standard to narrow band imaging (NBI) with the push of a button. In narrow band endoscopy, filtered light is used to preferentially enhance the mucosal surface, especially the network of superficial capillaries. Narrow band imaging is often combined with magnification endoscopy. Both adenomas and carcinomas have a rich network of underlying capillaries and enhance on NBI, thereby appearing dark brown against a blue-green mucosal background.5 The use of white light as well as NBI has enabled endoscopists to provide an immediate assessment of small colonic lesions without histopathologic evaluation.7 Gastric mucosal abnormalities are also differentiated by NBI with and without magnification endoscopy.8 NBI can also differentiate squamous from nonsquamous epithelium to help identify Barrett's esophagus (Figs. 3-1 and 3-2).

Autofluorescence

Autofluorescence endoscopy has been shown in pilot studies to improve the detection of dysplasia in Barrett's esophagus and chronic ulcerative colitis. Autofluorescence endoscopy relies on several principles: tissue architecture changes, such as mucosal thickening, dampen submucosal autofluorescence; neovascularization alters the light-emitting and scattering properties of surrounding tissue; the biochemical microenvironment, such as high oxidation-reduction activity, alters autofluorescence; and different tissue types have unique distribution of fluorophores.4,9

Optical Coherence Tomography

Endoscopic optical coherence tomography (OCT) is an emerging technology analogous to endoscopic ultrasound (EUS). OCT utilizes a probe passed via the endoscope, although it does not require tissue contact. The technique uses reflection of near-infrared light to produce real-time two-dimensional cross-sectional images of the gastrointestinal tract. These true anatomic images correspond to the histologic layers (mucosa, submucosa, and muscularis propria). The images obtained have a resolution 10-fold greater than EUS (Fig. 3-3). Preliminary studies have looked at the utility of OCT in the evaluation of Barrett's esophagus.10 Endoscopic optical coherence tomography is not yet in widespread use.

Light Scattering Spectroscopy

Light scattering spectroscopy mathematically analyzes the intensity and wavelength of reflected light to estimate the size and degree of crowding of surface epithelial nuclei. The technique relies on absorption and scattering of white light. Light scattering spectroscopy has shown limited efficacy in detecting Barrett's esophagus and early colonic dysplasia. The technique relies on graphing mathematical computations rather than an optical biopsy as is done in other emerging imaging techniques. Light scattering spectroscopy might be used in combination with optical biopsy for detection of early dysplasia.4

Image Documentation

Many gastrointestinal diseases require surveillance evaluation, and the progression or regression of identified disease state is vital to appropriate patient care. Video endoscopes produce digital signals that can be recorded on a variety of media, including film, hardcopy printout, disk, or a secure data file. During the procedure, it is imperative to visually document important findings and their location for comparison with previous or follow-up studies. This practice also allows other members of the health care team to understand and interpret the findings and plan for appropriate treatment. Additional documentation on anatomic diagrams will also facilitate interpretation. Pertinent negative findings should also be documented.

Endoscope Anatomy

Flexible endoscopes are being created in a wide variety of lengths and diameters, with an assortment of channel numbers and sizes, adjunct imaging modalities, and intrinsic and extrinsic scope mechanics for reducing scope looping and providing improved scope advancement. A basic understanding of the scope anatomy is vital to the performance of safe and effective flexible endosocpy.

Uniformally, the knobs for controlling manipulation of the scope tip are located on the right side of the headpiece, with an internal larger knob for upward and downward deflections and an external smaller knob, which manipulates the tip to the left and right. Locks accompany each knob to hold the deflection in position when needed. The ability for greater degree of deflection of the endoscope occurs with upward rather than downward manipulations. There is no variability in deflection provided by the right-left knob. In addition to manipulation of the deflecting knobs, significant scope rotation can be achieved by torquing the endoscope, altering the endoscopist's stance, or by rotating the headpiece while inserting or withdrawing the shaft of the endoscope.

There are two buttons on the front of the scope headpiece responsible for tip cleaning, air insufflation, and suction. The suction channel also functions as the biopsy channel so that any endoscopic tools placed into the biopsy channel will limit the ability to suction fluids through the endoscope. A small button on the front of the handpiece above the suction button allows for freezing of the image and digital recording by pressing the image capture button on the back of the handpiece. The endoscope is held in the left hand regardless of the individual physician's hand dominance. The internal up and downward deflection knob is controlled by the left thumb while the air, water, and suction by the left index and middle fingers. The smaller left-right knob then is usually manipulated by the right hand.

One of the challenges in modern endoscopy, especially colonoscopy, is the formation of undesired loops in the shaft of a flexible scope. Loop formation impedes expeditious and safe passage to the cecum by transmitting the force of insertion to the colon wall or mesentery rather than to forward progression. Two technical advances aim to prevent loop formation: variable stiffness endoscopes and shape-locking overtubes.

Variable Stiffness Endoscopes

Conventional colonoscopes have a static level of column strength throughout the length of the insertion tube. The column strength determines the amount of buckling of the instrument that occurs during insertion and the level of elasticity that remains during reduction of loops. Variable stiffness endoscopes permit alteration of the column strength through an adjustable tensioning coil (Fig. 3-4). The data from studies comparing variable stiffness colonoscopes to conventional scopes are inconclusive. Some studies report faster cecal intubation using variable stiffness endoscopes with less need for adjunct maneuvers, while other similar studies report no significant differences.11,12

Shape-Locking Device

The ShapeLock Endoscopic Guide (ShapeLock, USGI Medical, San Clemente, CA) consists of a reusable skeleton of multiple titanium links, a disposable inner plastic lining, an atraumatic foam tip, and a disposable smooth external skin. A squeeze handle at the base of the device converts it from a flexible mode to a rigid mode. The shape-locking device is made in 40 cm and 60 cm lengths with an inner diameter of 20 mm. A small clinical study has been reported using the shape-locking device. No device-related complications were noted, but the optimal strategy for employing the device was uncertain.13

New Scope Technology

While the construction of standard endoscopes has remained largely unchanged over many decades, novel scope designs are being developed to either simplify colonoscopic examinations or enhance mucosal visualization. Other than double balloon enteroscopy, these technologies are chiefly limited to small clinical trials, but their application could gain momentum in the coming years.

Self-Propelled Colonoscopes

In an effort to simplify the process of colonoscopic screening, self-propelled endoscopes are in development. The Aer-O-Scope (GI View, Ltd, Ramat Gan, Israel) is a user-independent, self-propelled, self-navigating colonoscope. The device consists of a disposable rectal introducer, supply cable, and a scope embedded within a scanning balloon. The device contains no working channel for therapeutic interventions; therefore, it is intended for screening purposes only. A small pilot study examined the proof of concept of the Aer-O-Scope. There were no device-related complications.4

Another self-propelled colonoscope, the ColonoSight (Stryker Corp, Kalamazoo, MI) employs air-assisted propulsion in a disposable system. A pneumatic mechanism generates the pressure to create the forward force, while an operator directs the scope using handles. The system uses light-emitting diode optics, rather than video or fiber optics, and has disposable working channels. A pilot study for ColonoSight reported intubation of the cecum in 88% of cases at a mean time of 12 minutes without any device-related complications.4

Endoscopic Education

Recent mandates from the American Board of Surgery now require surgical residents to graduate with an increased number of flexible endoscopy cases (50 colonoscopies, 35 esophagogastroduodenoscopies [EGDs]). To provide this experience and to improve the overall endoscopic education of surgery residents, a cohesive curriculum is needed.14 An iteration of such a curriculum might include periodic simulation training for first-year residents, formal endoscopy rotations for junior residents, and intraoperative and advanced endoscopy for senior and chief residents.15

Efforts to improve endoscopic training have led to the development of computer simulators for teaching endoscopic skills. Currently, simulators are available for training in flexible sigmoidoscopy, gastroscopy, endoscopic retrograde cholangiopancreatography (ERCP), EUS, and colonoscopy.16

Patient Assessment

Although both upper and lower endoscopy can be performed unsedated, the majority of patients undergoing endoscopic procedures receive agents to provide conscious sedation. Preprocedural patient risk assessment, intraprocedural cardiopulmonary monitoring, and postprocedural recovery are vital to the performance of safe and effective endoscopic interventions. Preprocedural evaluation for ASA risk classification and Malampati score have become standard guidelines for most endoscopy units.17 Elderly patients or those with preexisting cardiopulmonary conditions are at increased risk for these complications, as are those undergoing more extensive endoscopic interventions. Patients with diseases associated with the oropharynx or trachea, and those with morbid obesity, sleep apnea, or neuromuscular degenerative diseases require extra vigilance during endoscopic procedures.18

Monitoring

Monitoring should be performed before, during, and after the procedure by a dedicated endoscopy assistant. Signs that are routinely monitored include the patient's level of consciousness, degree of pain, vital signs, and respiratory status.19 Supplemental nasal oxygen is required to decrease the frequency of desaturation during endoscopic procedures. The patient's oxygenation status and cardiac electrical activity are also monitored by equipment throughout the procedure. It must be understood that pulsoximetry levels can rule out hypoxia and hypoventilation, and resultant hypercarbia can still go undetected. At this time, measurement of end tidal CO2 monitoring, however, is just beginning to be utilized at the time of endoscopic interventions. In addition, external suction for clearing oropharyngeal secretions must be immediately available and within reach of the endoscopic assistant.

Sedation

The combination of narcotics (analgesia) and benzodizepines (sedation and amnesia) is commonly used to provide sedation during endoscopic procedures.20 Although propofol has a more rapid onset and shorter half-life, its routine use during endoscopic procedures has been widely reserved for those performed in an operating room with an anesthesiologist.21 Reversal agents (antagonists) for both class of drugs are now available and should be immediately ready for delivery in patients who show signs of oversedation. Titration of medications delivered in small increments allows for the safe performance of sedated endoscopy, especially in older patients with slower circulatory distribution.

Cardiopulmonary issues are the most commonly reported complications with endoscopic procedures. These complications include aspiration, oversedation, hypotension, hypoventilation, arrhythmia, bradycardia (vasovagal), and airway obstruction. Many of the latter are associated with use of intravenous moderate (formerly “conscious”) sedation, defined as decreased consciousness associated with preservation of protective reflexes.

Indications

The indications for upper gastrointestinal endoscopy (EGD) can be divided between those for diagnosis and those to provide for potential therapy. Diagnostic EGD is used for the evaluation or surveillance of patients who present with “alarm symptoms” (Table 3-1) as do those with abnormal or inconclusive radiographic studies. Follow-up evaluations for ulcers or surveillance for patients with Barrett's esophagus are also indications. Therapeutic upper endoscopic interventions include the management of bleeding, removal or ablation of premalignant or malignant lesions, management of upper gastrointestinal obstructions, leaks or fistulae, and the creation of enteral access for supplemental feeding or decompression.

Contraindications

The contraindications to EGD are related to the patient's associated comorbidities, underlying gastrointestinal disorders, or patient's inability to tolerate conscious sedation. Recent myocardial infarction, pneumonia, and recent foregut surgical procedure are relative contraindications for EGD, and the risks and benefits need to be weighed on an independent basis for each patient to determine appropriateness. A recent surgical anastomosis is most likely safe at any time during the postoperative period to be evaluated endoscopically, remembering that tissue strength will be weakest on postoperative days five to seven.

Coagulopathy secondary to thrombocytopenia, liver failure, renal failure, or exogenous use of anticoagulants and platelet-inhibiting agents is a relative contraindication for a diagnostic EGD, but an absolute contraindication for a therapeutic intervention. Patient noncooperation and inability for a patient to be safely sedated due to high cardiopulmonary risk are also contraindications to EGD. Respiratory depression secondary to medications as well as inability to maintain an airway can occur in these high-risk patients. Preassessment with ASA classification and Malampatti scores will help predict this high-risk group. Patients with suspected perforation or caustic ingestion injury should not undergo EGD unless there are plans to provide palliative therapy such as endoscopic closure or stent placement.

Patient Preparation

Upper gastrointestinal endoscopy requires very little preparation other than fasting of solid food for 6–8 hours and liquids for 2–4 hours. Removable dentures and dental implants must be taken out to avoid dislodgement and aspiration during the procedure. The role of lavage in patients with bleeding is debatable, and if large volume lavage is to be used, care must be taken to avoid aspiration including the judicious use of endotracheal intubation. If intervention is anticipated, a recent coagulation profile and platelet count should be within safe ranges. The use of topical pharyngeal anesthetic spray is necessary in unsedated procedures in order to suppress the gag reflex, and is used based on physician preference for sedated cases.

The use of prophylactic antibiotics is rarely indicated for EGD, except in the scenario of esophageal sclerotherapy, dilation, and percutaneous endoscopic gastrostomy (PEG) tube placement. Discussion with the cardiologist as to the role of antibiotics is recommended for patients with prosthetic heart valves, previous endocarditis, systemic pulmonary shunts, or recent vascular prostheses.

Basic Endoscopic Techniques—Egd

The forward-viewing endoscope is preferred for routine diagnostic endoscopy. It should be noted that the medial duodenal wall, at the site of the ampulla, is preferentially seen with a side-viewing endoscope. More recently, the use of small diameter 5 mm transnasal endoscopes has allowed for the safe performance of unsedated endoscopy.

After appropriate preprocedural patient assessment and informed consent, the patient is routinely placed in a left side down lateral decubitus position. Patients undergoing PEG procedure or other therapies requiring access to the abdominal wall are left supine. Prior to delivery of sedation, a baseline set of vitals is taken and it is confirmed that the equipment is in proper working order and potentially necessary endoscopic tools are readily available. Following the slow delivery of medications, titrating the doses as needed based on the individual patient needs, the distal several centimeters of the endoscope are lubricated avoiding the actual tip of the endoscope as this will obscure the image and, even with irrigation, will make visualization difficult.

Intubation of the esophagus is best accomplished under direct vision by advancing the endoscope over the tongue, past the uvula and epiglottis, and then posterior to the arytenoid cartilages. This maneuver will impact the endoscope tip at the cricopharyngeal sphincter and allow entry into the cervical esophagus with gentle forward pressure once the patient swallows. Blind insertion with the endoscopist's hand in the patient's pharynx is not recommended as this is more dangerous for both the patient and the endoscopist.

Once in the cervical esophagus, the instrument is advanced under direct vision taking care to survey the mucosa during both insertion and withdrawal. The distance to the squamo-columnar junction, the “Z-line,” where the white squamous esophageal mucosa meets the red columnar gastric epithelium, is recorded in the procedure report. The site of the diaphragmatic crura (hiatus) should also be recorded and is seen as impression into the esophageal or gastric lumen. This point can be accentuated by asking the patient to sniff while the area is visualized. The endoscope is then advanced into the gastric lumen under direct visualization. Unlike colonoscopy where there is a requirement for significant torquing or twisting of the scope, due to fixation of the esophagus in the mediastinum, EGD manuipulations can be more directly achieved with deflection of the wheels and movement of the handpiece (“dancing with the scope”).

After aspirating any gastric contents, the four gastric walls are surveyed using combinations of tip deflection and shaft rotation, insertion, or withdrawal. During upper endoscopy, the endoscope will naturally follow the greater curvature as it advances toward the antrum and this is called the “long position.” This affords an end-on view of the pylorus, which is approached directly. Passage through the pylorus can usually be facilitated by gentle pressure and air insufflation. Entry into the duodenal bulb is recognized by the typical granular, pale mucosa without the folds of the valvulae conivente. Finally, the second portion of the duodenum is entered with the associated folds, by deflecting the tip up and to the right. In addition, rotating the handpiece to the right will help facilitate this maneuver. Withdrawal of the endoscope at this point while keeping the tip deflected leads to paradoxical advancement of the endoscope down the duodenum. Withdrawl of the endoscope places the shaft along the lesser curvature of the stomach and allows for this paradoxical forward advancement of the tip. This is referred to the “short position.” All areas should be carefully surveyed again as the endoscope is withdrawn.

The final component of a diagnostic EGD is evaluation of the cardia, fundus, and incisura along the lesser curvature. With a forward-viewing endoscope, these sites are visualized by a retroflexion maneuver with full upward tip deflection (Figs. 3-5 and 3-6).

Techniques of Endoscopic Tissue Sampling

Sampling of tissue is most frequently obtained by passage of a spiked forceps via the endoscope's biopsy channel. Multiple biopsies should usually be obtained. For ulcers, one should biopsy the edge of the lesion in at least four quadrants. Standard biopsy techniques are quite superficial; however, if deeper biopsies are desired, these can be obtained by using either a jumbo forceps or the practice of repetitive biopsies at the same site, which will lead to a deeper sampling.

Surveillance in diseases such as ulcerative colitis and Barrett's esophagus require a standardized sampling technique. Ulcerative colitis protocols recommend biopsies every 10 cm throughout the entire colon, and Barrett's sampling per the Seattle protocol requires at minimum 4-quadrant biopsies every 1 cm using a jumbo forceps. The goal of these sampling techniques is to identify the presence of dysplastic tissue necessitating further intervention.

Tissue and lesions can also be sampled by the use of brush cytology. In this technique, a sleeved brush is passed through the biopsy channel of the scope and rubbed forcefully over the desired site. The brush head is extended, stirred in a fixative solution to be spun down for cell evaluation, and then transected and dropped into fixative for direct cytologic analysis. The sensitivity and specificity of this technique are dependent on direct approximation to the diseased mucosa, and should not replace a directed biopsy if attainable.

Management of Bleeding

Endoscopy plays a critical role in evaluation and treatment of upper GI (UGI) bleeding. The degree of rapidity of UGI bleeding varies from severe with gross hematemesis to mild, presenting as either heme-positive stools or iron deficiency anemia. The timing for EGD should be based on each individual clinical scenario, understanding that endoscopy is both a diagnostic and a therapeutic tool. In all patients, hemodynamic stabilization and correction of any sources for ongoing coagulopathy are a priority.

Endoscopic hemostatic therapies can be divided into thermal and nonthermal categories. In addition, these hemostatic options can be further delineated based on specific ideal applications. There are associated risks with each of these techniques, which must be understood to allow for appropriate tool selection. It is also possible to treat bleeding with combined modalities such as coagulation and injection, or clipping and injection. When comparing individual therapeutic techniques, there is very little difference between them in terms of providing successful hemostasis. In fact, there are numerous studies to demonstrate the superiority of combined over single hemostatic therapy. Given the relatively high success rates of controlling UGI bleeding by endoscopic modalities, it is appropriate to pursue endoscopic means whenever available before seeking surgical or interventional radiology options.22

Thermal Techniques

Thermal therapies control hemorrhage by inducing tissue coagulation, collagen contraction, and vessel shrinkage. Thermal energy is delivered via a contact or a noncontact device. Thermal therapies are successful in 80–95% of cases, with a rebleed rate of 10–20%. These techniques are easy to use and safe, with a perforation rate of 0.5%, although this is dependent on the site of the gastrointestinal tract, with the cecum more likely to result in perforation than a thicker organ such as the stomach.23

Contact Thermal Techniques.

Contact or coaptive techniques involve the use of probes passed via the biopsy channel, which allow for pressure tamponade of the bleeding point with simultaneous application of thermal energy for coagulation. The firmer one applies the device to the tissue, the greater the depth of energy penetration. In addition, the tamponade not only improves visualization, but also reduces the “heat sink” effect of active bleeding, and thereby improves the efficiency of the coagulation process. Multipolar (bipolar) cautery (Fig. 3-7) and heater probe devices are used most commonly, although monopolar cautery via a biopsy forceps or snare may also be employed, albeit with a potentially higher risk of injury. The heat generated, which can reach several thousand degrees, is sufficient to cause full-thickness tissue damage, so care is required when using this modality.

Both cautery and heater probe units allow pulse irrigation to be performed for visualization and clot clearance via foot pedal control. Variables important in achieving hemostasis include probe size, force of application, power setting, and duration of energy delivery.23,24 Vessels of up to 2 mm in diameter appear to be able to be well controlled by these techniques although the overall surface area treated by these devices is limited by the size of the probes.

Noncontact Thermal Techniques.

Argon plasma coagulation (APC) is a technique in which thermal energy is applied to tissue via ionized argon gas. This technique has the disadvantage of not allowing a tamponade effect, but conversely is not prone to adherence of the probe to the hemostatic coagulum. The gas has an effect of clearing luminal liquid from the point of application; however, due to the high pressure of gas delivery, one must be careful to avoid overdistention of the lumen by using frequent suctioning during APC usage. It is more widely utilized in most centers than laser, and in limited studies appears to have similar efficacy to contact probes.24

APC is particularly well-suited for settings where large mucosal areas require treatment such as gastric antral vascular ectasia (GAVE) (Fig. 3-8), or where the risk of deeper thermal injury leading to perforation is of heightened concern, for example, cecal angiodysplasia.

Nonthermal Techniques

Injection Sclerotherapy.

Injection therapy is performed by passage of a catheter system through the biopsy channel of the endoscope. There is an internal 5-mm needle, which can be advanced and withdrawn as needed. The sclerosant is injected submucosally. Injection therapy at three or four sites surrounding a bleeding site prior to contact thermal techniques may prove more effective, as the created eschar is occasionally removed inadvertently affixed to the treating probe. If tamponade is provided first with injection therapy, bleeding following initial thermal therapies can be reduced. The amount injected varies with different agents, and it must be remembered that systemic absorption will occur. Dilute 1:10,000 epinephrine solution is the most commonly used agent, and should be limited to less than 10 cc total volume. Other agents available include absolute alcohol, thrombin in normal saline, sodium tetradecyl sulfate, and polidocanol.22,23 For esophageal varices, injections are begun just above the gastroesophageal junction. Sclerosants can be injected either directly into the varix or along side it, intravariceal or paravariceal. Variceal banding with endoscopic band ligators, although associated with a slightly higher rate of rebleeding, has predominantly supplanted injection sclerotherapy due to lower complication rates. In the absence of active bleeding or stigmata of bleeding, prophylactic endoscopic variceal eradication should not be performed because of the high risks of complications associated with the procedures. In patients with severe variceal bleeding or recurrent bleeding following endoscopic therapies, other options such as transjugular intrahepatic portosystemic shunt (TIPS) or surgical portosystemic shunting should be considered (see Chap. 47).

Endoscopic Ligation Techniques

Endoscopic Band Placement.

Endoscopic band ligating systems are readily available and provide an alternative for management of variceal and nonvariceal bleeding, and are also routinely used in conjunction with endoscopic mucosal resection (EMR) techniques. This technique is based on the ability to suction tissue into a cap placed at the tip of the endoscope, and then with the turning of a control knob, fire a small tightly constricting rubber band. Single band devices were initially developed for the treatment of esophageal varices, but there are now numerous multiband ligating systems. This innovation provided an alternative to injection sclerotherapy, and although it proved to be slightly less effective in preventing recurrent bleeding, complications such as stricture formation have been dramatically reduced. Applications for endoscopic banding include treatment of internal hemmorhoids, dielufoy ulcers, esophageal and gastric varices, and mucosal neoplasia in conjunction with EMR.25

Endoscopic Suture Placement.

Pretied endoscopic loops can also be applied through a standard endoscope biopsy channel, and can be used for ligation of pedunculated structures before or after endoscopic resection. These single application devices are similar to laparoscopic endoloops, although they are nylon sutures, and instead of an actual slip knot, a plastic cinching device holds the loop in place once deployed. Use of a double channel endoscope, allowing for a two-handed technique to grasp the desired tissue and deliver it throught the opened loop, is preferred. Similar to clips, these sutures will routinely slough off the tissue in 1–2 weeks.

Endoscopic Clipping.

Endoscopic clip placement is an effective method to control bleeding and can be used safely at multiple sites throughout the gastrointestinal tract.26–28 Frequently, more than one clip is necessary at the site of bleeding (Fig. 3-9). The depth of tissue obtained by endoscopic clip placement is quite superficial, with only the mucosa routinely being captured. Clips are placed via the biopsy channel of the scope and come with varied application and shape qualities. Rotatable clips as well as clips that can be opened and closed prior to final positioning are available. In addition, clips with both two arms and three arms, as well as those that have single use and multiple use deployment systems are manufactured. These clips can effectively control bleeding, and usually fall off in 1–2 weeks. Cases of clips remaining at the site with and without mucosal overgrowth months after placement have been reported.

Endoscopic Mucosal Resection

The treatment of premalignant as well as superficial cancers can now be managed by endoscopic resective techniques. EMR has been employed for adenomas, dysplastic lesions, and early-stage carcinomas, including lateral spreading tumors.29 Carcinomas without submucosal invasion or nodal spread might be amenable to EMR. Although these diseases are less commonly seen in Western societies, the use of these techniques is routine throughout Asian populations for treatment of esophageal and gastric lesions. Conversely, colonic lesions in Western countries are routinely managed with these modalities. CT scan and EUS are recommended to assess for nodal disease prior to EMR. Multiple technical variations of EMR for the upper and lower tract have been developed, including submucosal injection, “suck-and-cut,” “suck-and-ligate,” and strip biopsy.

Saline Lift Emr

The most commonly performed EMR technique employs submucosal injection of a fluid followed by electrosurgical polypectomy. Initially the margins of the lesion are clearly delineated, and the periphery is marked using short burst of electrocautery. A standard sclerotherapy needle is then used to perform a submucosal injection. The most commonly used fluid is saline with or without epinephrine, although hyaluronic acid, glycerol, and dextrose have all been described. A bleb is created with the submucosal injection creating space between the line of resection and the muscularis propria of the organ, and the lesion is resected (Figs. 3-10 to 3-12). Repeat injection of agent is commonly needed due to absorption as well as diffusion of the fluid. Injection beyond the lesion first allows for better imaging of the tissues. Intralesional injection can also be used prior to resection. One caveat to this technique is that if the submucosal injection does not result in elevation, one must consider that this mass is an invasive lesion and should not be resected endoscopically. Multiple biopsies as well as EUS should be performed.

“Suck‐and-Cut” Emr

The “suck-and-cut” technique uses a specially designed cap attached to the tip of the endoscope. A submucosal injection may be created a priori and the lesion is sucked into the cap. A snare affixed to the cap is used to encircle the lesion, which is then resected by application of electrocautery. Similar to any thermal technique, risk of perforation exists. In addition, the depth of tissue acquisition is not well controlled, and care should be taken to avoid inadvertent perforation, especially in thinner walled organs such as the cecum.

“Suck‐and-Ligate” Emr

The “suck-and-ligate” technique transforms a sessile or nodular lesion into an artificial pedunculated polyp, which can then be resected with standard polypectomy techniques. A band ligating device is attached to the tip of the endoscope and the tissue is sucked into the cap and a band is placed at the base of the lesion. This is done with or without saline lift injections prior to banding. This serves to separate the mucosal lesion from the submucosa, permitting safe resection using a standard polypectomy snare.

The most frequent complications of EMR are bleeding and perforation. Immediate bleeding can be controlled with endoscopically placed clips or injection of dilute epinephrine. Electrocautery should be used judiciously after EMR because the thin submucosa and serosa are susceptible to full-thickness injury with cautery. Delayed bleeding often requires repeat endoscopy with injection therapy or clip application, although angiography and embolization may be an alternative. Perforations can also be managed endoscopically with endsocopic clips as well as temporary enteral stent placement to cover the site of perforation.

Endoscopic Submucosal Dissection

An extension of EMR that has been recently reported for endoscopic resection of more extensive lesions is endoscopic submucosal dissection (ESD). Utilizing a combination of needle cautery and blunt endoscope cap dissection, large segments of tissue can be resected. Two-handed techniques utilizing a double channel scope is vital. Circumferential segments of tissue can be removed, although these are lengthy and very challenging procedures. The advantage of ESD is that it represents a more classic oncologic maneuver, as compared to the piece meal resection that occurs with other EMR techniques, in that margins as well as lesion depth can be more accurately pathologically evaluated. Complications are higher than for the other EMR techniques, including bleeding, perforation, and stricture formation which can occur in almost 20% of cases.29

Endoscopic Mucosal Ablation

Endoluminal therapies for ablation of mucosal-based diseases such as Barrett's esophagus have recently seen great advances. Previously, photodynamic therapy was the principal technique used, but the associated complications and the side effects related to the delivery of the sensitizing agent were high. Endoscopic radiofrequency ablation (RFA) is a relatively new technology that has recently gained acceptance for treatment of intestinal metaplasia as seen in Barrett's esophagus.30 Its unique design incorporates bipolar radiofrequency energy and applies it directly to the esophageal epithelium for ablation. A balloon-based system, as well as a directed planar electrode device implementing this technology, has been used in this form of therapy. The balloon-based model has proved to be safe for Barrett's esophagus.29 The HALO90 system (BÂRRX Medical, Sunnyvale, CA) is an endoscopic RFA device composed of an ablation electrode that is mounted to the end of a flexible endoscope.

There is a 13 mm (width) × 20 mm (length) planar electrode on the face of the probe that delivers the designated energy. The electrode has a 4-mm diameter catheter that runs from the device along the endoscope and is connected to an RFA generator. The generator can be altered to vary energy density [joules/centimeter2 (J/cm2)] and power density (watts/cm2). This endoscopic RFA technology also delivers a controlled amount of energy to the tissue that is predetermined prior to firing, whereby limiting unintentional transmural and potentially extralumenal injury.

Several studies have proven feasibility and safety for this novel therapy, with very few documented cases of postprocedural structuring as had been seen with photodynamic therapy (PDT).31–33 Further studies documenting long-term effects of this therapy, as well as the absence of buried submucosal metaplastic glands or cancer, are still necessary.

Endsocopic Enteral Access

Endoscopic access to the gastrointestinal tract has become one of the most common endoscopic procedures now performed. What had previously required surgical intervention is routinely managed endoscopically. Gastric access (PEG), jejunal access (direct percutaneous endoscopic jejunostomy [PEJ]), or a combination of both (PEG with jejunostomy tube extension [PEG-J]) can be provided. Indications for access include supplemental feeding, decompression, fixation of structures, and access for meds. There are only a few absolute contraindications to endoscopic enteral access including esophageal obstruction and limited life expectancy. Patients with expected survival of less than 4 weeks should not undergo these procedures. Relative contraindications requiring individual patient selection include severe malnutrition, ascites, prior abdominal surgery, prior gastric resection, peritoneal dialysis, coagulopathy, and gastric malignancy.

Percutaneous Endoscopic Gastrostomy

PEG is now the preferred method for long-term feeding in patients who are unable to swallow or who require supplemental nutrition or chronic gastric decompression. PEG may be preferable to surgical gastrostomy since it is safe, less expensive, and less invasive. A variety of PEG techniques are available including “pull,” “push,” and “introducer”. “Pull” and “push” techniques require passage of the tube via the oropharynx and it is proposed that infectious risks and seeding of oropharyngeal cancers might be increased as compared to “introducer” technique, where the tube is placed percutaneously through the abdominal wall under endoscopic guidance. This theory has yet to be proven in randomized prospective trials.

Prior to any PEG procedure, a single dose of prophylactic cephalosporin (or equivalent) should be given intravenously. The patient is placed in the supine or semi-Fowler position with the head elevated and the arms held with soft restraints, after which the abdomen is prepared and draped using sterile technique. The endoscope is then passed into the stomach, which is distended with air insufflation. It is recommended to perform a brief but complete endoscopic evaluation of the esophagus, stomach, and duodenum to rule out any coexistent disease, which might require treatment or complicate the PEG procedure. The assistant then presses on the abdomen with a single finger and the impact against the anterior gastric wall should be noted. Ideally, this point should be 2–3 cm below the costal margin and the maximal point of impression may be on either side of the abdominal wall or subxyphoid. Light transillumination from within the stomach to the skin surface may aid in identifying a safe landmark. Finally, it is imperative to perform a “safe tract” technique to assure that there is no intervening hollow viscus between the stomach and anterior abdominal wall. After anesthetizing the skin, a syringe with saline or local anesthetic is passed through the abdominal wall at the selected site while aspirating. As soon as air is appreciated in the syringe, the tip of the needle should be simultaneously visualized by the endoscopist in the gastric lumen. If not, an alternative site needs to be selected.

The endoscopist now passes a polypectomy snare through the endoscope channel at the selected intragastric site. A small transverse incision (approximately 7–9 mm) in the skin is created and the assistant then inserts a 14-gauge intravenous cannula through the incision into the gastric lumen. The snare is then tightened around the cannula and the inner stylet is removed.

“Pull” Peg.

In the “pull technique,” a long looped suture is placed through the cannula, after which the snare is released. The suture is then firmly grasped with the polypectomy snare. The endoscope and the tightened snare are removed together, bringing the suture out of the patient's mouth. The suture is secured to a well-lubricated gastrostomy tube at its tapered external end. The assistant then pulls on the suture until the attached tube exits the abdominal wall. The endoscope is then reinserted and used to view the tube's inner bolster (Fig. 3-13) as the stomach is loosely seated against the abdominal wall and the tube is properly positioned. This second intubation of the endoscope can be aided by grasping the PEG bumper with the snare passed through the endoscope. With withdrawl of the PEG through the mouth and out the abdominal wall, the endoscope is reintroduced into the esophagus. The snare is opened after esophageal intubation. The external bumper is placed loosely so that there is no tension at the PEG site and the endoscope is then removed.

“Push” Peg.

In the “push technique,” a guide wire rather than a looped suture is inserted through the cannula and pulled out the patient's mouth. The gastrostomy tube, called a Sachs-Vine tube, has a long tapered tip, which can be pushed over the wire until it exits the abdominal wall. A second endoscopic intubation is recommended similar to the “pull” technique.

“Introducer” Peg.

In the “introducer technique,” a guide wire is passed through the cannula placed into the stomach under endoscopic guidance. An introducer with a peel-away sheath is then passed over this wire, allowing removal of the wire and introducer. A Foley catheter or other similar gastrostomy tube is then placed through the sheath, its balloon is inflated, and the sheath is removed. The catheter is then secured to the abdominal wall. The placement of T-tags prior to performance of the introducer PEG can help to secure the stomach to the abdominal wall.

Laparoscopic-Assisted Peg.

In patients with morbid obesity, prior surgery, or intrathoracic gastric positioning, where safe access cannot be adequately determined by routine endoscopic techniques, simultaneous laparoscopy and endoscopy can be performed to complete the PEG safely. In this way, a long spinal needle can be passed under direct laparoscopic view from the abdominal wall into the gastric lumen and the PEG can be completed as described above.

Interventional Radiology–Assisted Peg.

In patients with a “hostile” abdomen secondary to malignancy, multiple prior surgeries, or obesity where safe access cannot be endoscopically determined and laparoscopy would be challenging, a percutaneous intragastric pigtail catheter can be placed by interventional radiology under CT or ultrasound guidance. Utilizing a rendezvous technique, a guide wire is then advanced through the pigtail during upper endoscopy, and the PEG is completed.

Peg with Jejunostomy Tube Extension.

In patients who fail to tolerate gastric feedings due to severe gastroesophageal reflux or gastroparesis, transpyloric feeding can be provided via a jejunostomy tube passed through the existing PEG. There are no prospective randomized trials, however, showing a difference between intragastric and transpyloric feeding, in terms of incidence of aspiration pneumonia. The majority of cases of aspiration pneumonia are related to aspirated oropharyngeal secretions in a patient unable to protect their own airway.

PEG-J placement is achieved by passing a jejunal feeding tube through the PEG lumen (a 24 Fr PEG tube accommodates up to a 12.5 Fr J-tube; a standard 20 Fr PEG tube accommodates an 8.5 Fr J-tube). Endoscopically, the jejunal tube is guided into the duodenum under direct vision. A loop suture on the tip of the jejunostomy tube can be grasped by an endoscopic clip and once in the distal duodenum, the clip is deployed onto the small bowel mucosa to secure the tube in place. These clips routinely fall off in 1–2 weeks, but this technique allows for easier removal of the endoscope from the duodenum without simultaneous inadvertent withdrawal of the J-tube at the end of the procedure.

Direct Percutaneous Endoscopic Jejunostomy Tube

In patients with confirmed aspiration secondary to gastroesophageal reflux of intragastric feedings, direct PEJ rather than PEG-J is of benefit. Feedings beyond the ligament of Treitz are associated with a lower incidence of gastroesohpageal-induced aspiration as compared to simple postpyloric feeding.34 Direct PEJ, however, is associated with increased procedural risks including bleeding, inadvertent viscus injury, and leakage.35–38 Performance of direct PEJ requires both endoscopic and fluoroscopic guidance. Utilizing a pediatric colonoscope, the proximal jejunum is intubated and the tip of the endoscope is fluoroscopically visualized. Abdominal wall depression with a haemostat is performed at this site to try to identify a loop of small bowel adjacent to the abdominal wall. Safe tract techniques are then used to access the identified bowel and a “pull” PEJ is performed with either a 16 Fr or 20 Fr tube. Second intubation with the endoscope to the PEJ site is mandatory to assure intraluminal positioning of the jejunostomy tube bumper.

Foreign Body Extraction.

Foreign bodies are ingested predominantly by two groups of patients: children (ages 1–5 years) who accidentally swallow an object, and adults, who are obtunded or inebriated, have a psychiatric disorder, or are prisoners.39,40 Food impaction may occur in patients who have an underlying benign or malignant esophageal stricture, or in patients with esophageal motility disorders.41 Also, patients who are edentulous or have poor fitting dental prostheses are at risk for food impaction of poorly chewed meat boluses. Evidence of respiratory compromise or an inability to handle one's own secretions indicates an immediate need for endoscopic evaluation and extraction of the object.

When performing endoscopic extraction, protection of the airway is of vital importance. Endotracheal intubation is required in patients who are unable to handle their own secretions. An endoscopic overtube should be considered when there is concern for dropping pieces into the airway such as when removing sharp objects or multiple fragments. In addition, practicing with a similar foreign body prior to an attempted removal will allow for selection of the most appropriate endoscopic tool.

Coins represent the most object swallowed by children, and if seen to be in the esophagus should be removed promptly due to the risk of pressure necrosis and fistula formation.39 The coin is localized and grasped with a polypectomy snare, net, or rat-tooth or tenaculum forceps. A Foley catheter is not recommended since it does not control the object well during removal and could become dislodged into the airway.

In the adult population, meat impaction represents the most common foreign body and should be removed if they remain for longer than 12 hours due to the risk of pressure necrosis.41 Gentle scope advancement at the level of the obstruction can many times assist in passage of the food bolus. Piecemeal removal with baskets, nets, and snares may be needed, with care being taken to avoid passage of the foreign body into the airway. If the bolus should pass, EGD is still indicated to rule out an associated esophageal lesion.41

Use of an overtube or protective endoscopic hood may greatly facilitate removal of sharp objects such as toothpicks, fish or chicken bones, needles, and razor blades. When removing sharp objects it is important to follow the tenet of always having the sharp end trailing. If necessary, sharp objects can be carefully pushed into the stomach, rotated, and then brought out with the pointed end trailing.

Ingested button batteries must be removed immediately to prevent viscus injury secondary to a corrosive burn. These batteries usually pass readily in other parts of the gastrointestinal tract without causing harm, although all mucosal surfaces must be examined endoscopically to identify any resultant injury.

When encountered, cocaine-filled packets should never be removed endoscopically because of the risk of breakage. Close observation and expectant management is more appropriate, with expedient surgical intervention for any signs of bag rupture or bowel obstruction.

Following any foreign body removal, the endoscopist must exclude any associated underlying disease such as stricture, neoplasm, or motility disorder (Fig. 3-14). In addition, one must be aware of the possibility of delayed viscus injury secondary to pressure necrosis resulting in partial or full thickness injury. Emergent contrast study or CT should be used as needed to evaluate for these complications. Repeat endoscopy, motility study, or elective contrast studies may also be required based on patient's history or continued symptoms.

Other nonobstructing foreign bodies may be identified in postsurgical patients. Intraluminal suture migration may lead to symptoms of pain or dysphagia. (Fig. 3-15). Removal with endoscopic scissors may relieve the patient's symptoms of pain or dysphagia.

Endoscopic Dilation.

Endoscopic dilation can be performed for any enteral stricture that can be accessed by endoscopic means. The endoscopic component of dilation may include identification, passage of a guide wire, or delivery of a dilating balloon via the endoscope channel. Strictures secondary to ischemia, inflammation, radiation, neoplasm, and postsurgery are all amenable to endoscopic dilation. The use of fluoroscopy as an adjunct to endoscopic dilation is believed to decrease the risk of perforation, although this has not been fully proven in randomized prospective trials.42 In addition, the type of sedation utilized is dependent on the clinical status of each individual patient, as those with tight esophageal strictures may be best served with elective airway protection.

Although several types of dilators have been used, the two most common dilators used are the guide wire–driven type, which applies both axial and radial forces, and the balloon type, which applies only radial forces. Treatment is safer when performed by incremental dilations over successive sessions. A general approach is to limit the number of dilations to three successive balloon or dilator sizes in one session. Injection of steroid solutions (kenalog) into the stricture may reduce the severity of postdilation inflammation, scarring, and restricture. The frequency of dilation will depend on the severity of the stricture and the patient's symptoms.

Balloon dilators are used for short strictures, stenotic stomas, and achalasia. These dilators can be passed over a previously placed guide wire, and are delivered through the endoscope's therapeutic channel. Fluoroscopic guidance for balloon dilation allows the endoscopist to gauge several components of the procedure. First, it assures the positioning of the balloon in the viscus lumen. Second, if contrast is injected in the balloon as the dilating fluid, expansion of the balloon fully can be appreciated. This is termed “waist ablation” and refers to the full dilation of the balloon at the site of the stricture. The balloon changes from an hour glass appearance to a full elliptical-shaped figure.

Long, complex strictures may be less responsive to endoscopic dilation, and may also require repeat treatments. Aggressive biopsing of the mucosa after dilation is necessary in cases of unclear etiology. Complications secondary to endoscopic dilation include bleeding, perforation, mucosal tears, and recurrent structuring.

Enteral Stent Placement.

Over the past several years, endoscopic stent technology has made impressive strides in providing tools for increasingly complex clinical scenarios. Both the delivery systems and the stents themselves have gone through significant changes and allowances for treatment of a multitude of benign and malignant disease processes. Strictures, leaks, fistulae, and obstructing neoplasms have all been approached with enteral stents.43–50

Stent Delivery Systems.

Based on the location of the gastrointestinal tract that is to be treated, as well as the characteristics of the stent desired, endoscopic stent deployment is either through-the-scope (TTS), or wire guided. TTS stents are delivered through the endoscope channel and are routinely a 10 Fr system and require a therapeutic scope. Only uncovered self-expanding metal stents (SEMS) have a TTS characteristic. The remainder of stents all utilize wire guided systems and are placed under fluoroscopic guidance. Stent delivery systems are further categorized as proximal or distal deploying based on which end of the stent is opened first. In patients undergoing stent placement in the proximal esophagus, proximal deploying stents are preferred. Otherwise, most stent systems utilize a distal deployment pattern. Non-TTS stents are limited to the esophagus including the esophagogastric junction. In patients following gastric resection, these systems can also traverse a gatrojejunal anastomosis. TTS systems, conversely, can reach any site in the gastrointestinal tract that can be accessed by a therapeutic endoscope.43

Stent Characteristics.

Covered endoscopic stents have been created for the sole purpose of temporarily bridging esophagaeal and proximal anastomotic leaks and fistulae.45 The fully covered nature of the stent impedes tissue ingrowth as would occur with an uncovered enteral stent, and thereby allows removal after 2–3 months once the fistula has been cured. With the increased frequency of bariatric procedures, anastomotic complications secondary to Roux-en-Y bypass are routinely managed with placement of endoscopic stents.

Removable stents are subdivided into plastic or hybrid based on the underlying structural platform. As stated above, fully covered silicone stents which are self-expandable but require the use of a large deployment system, can reach as far as the proximal stomach. Similarly, covered SEMT (hybrid) are also placed outside of the endoscope under fluoroscopic guidance, and can reach the proximal stomach as well. The greatest problem with these stents is the high risk of migration.45 If placed across a gastrojejunostomy, this can result in small bowel impaction of a migrated stent, resulting in the need for surgical extirpation. Bleeding, perforation, and obstruction are far less common complications.

Uncovered enteral stents, utilizing TTS deployment systems, are not intended for removal and can be placed for temporary relief of benign and malignant strictures throughout the gastrointestinal tract.43,44,46–48 They are associated with increased tissue ingrowth and occlusion as compared to covered stents, but have a lower rate of migration. In unresectable disease states, palliation of obstruction with enteral stents can provide an alternative to surgical bypass procedures. In addition, endoscopic stent placement in patients with obstructing colon lesions can allow for immediate decompression followed by semielective resection and primary anastomosis, rather than an initial diverting stoma.49,50

Endoluminal Treatment of GERD

Numerous endoluminal treatments for gastroesophageal reflux disease (GERD) have been introduced over the past 10 years and have had varied clinical success. These technologies were based on either suturing, tissue bolstering, or energy delivery. Unfortunately, due to many factors including marginal patient improvement, limited physician acceptance, severe complications, and corporate financial difficulties, most of these treatments are not presently available in the United States. Examples of each of these modalities are described below.

Endocinch (Bard, Billerica, Ma)

The EndoCinch plication device (CR Bard, Inc, Murray Hill, NY) creates an internal mucosa-to-mucosa placation of the stomach. Using a standard endoscope outfitted with the device at its tip, the tissue is drawn into the suturing chamber by suction, and two sutures are placed. The knots are formed extracorporally and advanced to the gastric mucosa. While some of the short-term results were promising, the long-term results were bleak, confirming the lack of durability of a mucosa-to-mucosa apposition. This product is not presently being marketed for GERD treatment. Most authorities agree that technical refinements would be necessary before the EndoCinch can be effectively used for gastroplication.51,52

Stretta (Curon Medical, Sunnyvale Ca)

This is the only device that involves delivery of radio frequency energy to the lower esophageal sphincter (LES) muscles. Multiple applications at several levels are required to complete the treatment. The procedure is performed blindly after endoscopically confirming the location of the LES. The intention is to induce collagen deposition to the LES, thereby adding more bulk and reducing the compliance of the LES. The effects are generally not immediate, but are realized over time. Despite modest success with this device, the company declared bankruptcy in 2007.53–57

Plicator (Ndo Surgical, Mansfield Ma)

The NDO endoscopic plication system (NDO Surgical, Inc, Mansfield, MA) performed serosa-to-serosa apposition of the stomach just distal to the esophagogastric junction. The reusable device included a suturing mechanism at its tip and a channel for passage of a small bore endoscope for visualization. The single-use suturing implant used pretied polypropylene sutures with polytetrafluoroethylene bolsters. A proprietary retraction device selected the tissue for plication before deploying the sutures with a turn of the handle. Similar to Curon, this company also had significant financial difficulties and declared bankruptcy in 2008.58–61

Enteryx (Boston Scientific Corp, Natick, Ma)

For augmentation of the LES, the Enteryx system used a biocompatible, nonbiodegradable polymer. The solution contained a liquid polymer and radiopaque material to gauge the depth of injection. A circumferential injection of the polymer is performed, and its subsequent solidification tightens the esophagogastric junction. Multiple recent studies employing the Enteryx system have been published. Of note, Deviere and colleagues described the first sham-controlled trial with Enteryx in 2005.62 Of the 64 patients, 83% reduced proton pump inhibitor (PPI) use by 50%, and 68% had discontinued PPIs. However, in the sham arm, 53% had halved their PPI use, and 40% discontinued PPIs. There was no objective improvement in pH values. Due to severe adverse events related to intra-aortic injections and subsequent fatal fistulization, the product was voluntarily discontinued by the company.62–68

Gatekeeper (Medtronic, Inc, Minneapolis, Mn)

The Gatekeeper reflux repair system alters esophagogastric junction anatomy in order to restrict the aperture for reflux. A saline lift is performed above the squamocolumnar junction, and a biocompatible cylindrical prosthetic composed of polyacrylonitrite hydrogel is placed in the submucosa. The prosthetic subsequently enlarges with hydration, thereby impeding gastroesophageal reflux. There were two significant complications and the manufacturer has since withdrawn the Gatekeeper system from the market.69,70

Esophyx (Endogastric Solutions, Redwood City, Ca)

EsophyX is a novel endoluminal fundoplication technique using a trans-oral fastener-deploying device, attempting to mimic a Nissen fundoplication. In a feasibility study from Belgium, the results at 2 years supported long-term safety and durability with a sustained effect on the elimination of heartburn, esophagitis, hiatal hernia, and daily dependence on PPIs. At 2 years, no adverse events were reported, and a 50% or greater improvement in GERD-HRQL scores as compared with baseline on PPIs was sustained by 64% of patients. Esophyx was effective in eliminating heartburn in 93% of patients and daily PPI therapy in 71% of patients. Further clinical trials directly comparing this procedure to medical or surgical therapy are still necessary.53

History

William McKune, a surgeon, along with Paul Shorb, a gastroenterologist, were the first physicians to perform ERCP. In 1968, they reported on four cases of endoscopic identification and catheter placement into the ampulla of Vater. For the first time, imaging of the pancreatic ductal system could be seen and utilized for diagnostic purposes. Several years later in the mid-1970s, German and Japanese physicians described their experience in endoscopic sphincterotomy, the first therapeutic extension of ERCP. Other endoscopic adjuncts including stone lithotriptors, plastic and expandable metal stents, and intraductal imaging tools have fully changed ERCP from a diagnostic tool into one that is predominantly therapeutic.

Indications

There are numerous indications for ERCP as listed in Table 3-2. ERCP, however, is preferentially used as a therapeutic tool due to the high risk of serious complications.71 In patients where a diagnostic imaging of the pancreticobiliary tree is desired, magnetic resonance cholangiopancreatography (MRCP) should be utilized.72 Prior to cholecystectomy for symptomatic cholelithiasis, the presence of persistent jaundice or cholangitis is the indication for preoperative ERCP. Finally, as the number of patients undergoing bariatric procedures (Roux–en-Y gastric bypass) increases, access to the ampulla has become more challenging. Identification and access to the remnant stomach routinely require surgical or radiologic intervention for performance of ERCP.

Patient Preparation

Patient preparation, sedation, and monitoring for ERCP are similar to those for other upper endoscopic procedures, although the patient is routinely placed in the prone positon. Patients may require general anesthesia for airway protection, inability to tolerate conscious sedation, for expected lengthy or more complicated ERCP interventions, or in the presence of multiple comorbid diseases. ERCP can be performed in a supine position although this can make the procedure more challenging, as in patients undergoing ERCP at the time of laparoscopic cholecystectomy.

Techniques of ERCP

ERCP is performed using a side-viewing scope and requires both endoscopic and fluoroscopic skills for interpretation and intervention. As stated above, ERCP is predominantly a therapeutic technique. The scope is initially passed into the esophagus blindly to a position beyond the upper esophageal sphincter and then rapidly advanced into the proximal stomach where any residual secretions should be aspirated Unlike a forward-viewing endoscope, the pylorus cannot be visualized during intubation with a side-viewing scope.

Upward deflection of the side-viewing endoscope with continued advancement will allow easy passage into the duodenal bulb.

To manipulate around the superior duodenal angle, the endoscope is turned to the right, and the tip is deflected upward to reach the second portion of the duodenum. The endoscope is then withdrawn during this maneuver, leaving the scope in the ideal “short-scope” position.

With the “short-scope” position, the endoscopist views the papilla directly along the medial duodenal wall. Very minute movements of the tip and further withdrawl of the scope will bring the papilla into view. Intermittent doses of glucagon can be given to minimize duodenal peristaltic contractions. Dosing with glucagon, however, can lead to increased postprocedure nausea and vomiting. Fluoroscopy can also be used to determine appropriate scope position and to help identify the site of the major papilla. After the papilla is visualized, it is then cannulated using one of the various types of catheters available. As the majority of ERCP cases are potentially of a therapeutic nature, most endoscopists will start with a pull wire sphincterotome. Guide wire–assisted cannulation has also become a popular practice for several reasons. First, it may minimize the overall volume of contrast required, thereby hopefully decreasing the rates of pancreatitis and cholangitis. Second, it may increase the efficiency of selectively cannulating the desired duct. Finally, it can help maintain access into the duct during catheter exchanges.

Selective cannulation of the biliary and pancreatic ducts depends on the angle of the catheter and the position of the scope tip. The pancreatic duct tends to enter the papilla in a relatively perpendicular fashion at the 1-o'clock position. In contrast, the bile duct runs toward 11 o'clock below the “lip” of the papilla.

ERCP represents an endoscopic and radiographic intervention, and proper radiologic technique is critical to obtaining interpretable radiographs. Artifacts such as air bubbles, streaming and layering of contrast, and contrast spillage into the duodenum should be recognized and avoided.

ERCP Therapeutic Interventions

Sphincterotomy

There are two types of sphincterotomy that can be performed, needle knife sphincterotmy (precut sphincterotmy) or pull wire sphincterotomy. Needle knife sphincterotomy is performed when deep selective canulation is unable to be obtained, and can be done over a previously placed stent or guide wire, or when an impacted common bile duct (CBD) stone is protruding through the ampulla (Fig. 3-16). This technique is more technically challenging and also has a higher risk of bleeding, pancreatitis, and perforation. Pull wire sphincterotmy, conversely, requires deep selective canulation with or without previous wire placement.

Once proper selective ductal cannulation is verified, the sphincterotome is withdrawn until approximately half of the wire is visible outside of the papilla (Figs. 3-17 and 3-18). Biliary or pancreatic sphincterotomy can be done as needed. Indications for sphincterotomy include treatment of sphincter of Oddi dysfunction (SOD), improved access for stone removal or stent placement, and recurrent pancretitis. To perform sphincterotomy, the pull-wire is tightened, bowing it against the papillary roof. Current is then applied while maintaining gentle upward force on the wire and gently lifting the sphincterotome, making the incision in small increments.

Management of Choledocholithiasis

Retained or recurrent CBD stones represent the most common indication for endoscopic sphincterotomy, and ERCP with sphincterotomy successfully treats 95% of these cases.73 In expert hands, over 90% of bile ducts can be successfully cleared of calculi with balloon catheters or Dormia baskets, resulting in an overall ductal clearance rate approximating 85% (Figs. 3-19 and 3-20). Stone size is often a limiting factor, as stones greater than 2 cm in diameter often require fragmentation prior to removal. The other reasons for unsuccessful ERCP include patient intolerance, inability to identify or access the papilla, and inability to selectively canulate the desired duct.

Routine preoperative ERCP and sphincterotomy are not warranted in patients undergoing biliary operations for symptomatic cholelithiasis.73 Unfortunately, determining the presence of CBD stones is challenging, as ultrasound findings of biliary dilation, elevation of liver function tests (LFTs), and clinical factors such as pancreatitis are not always predictive of CBD stones. Only the actual radiographic finding of choledocholithiasis is statistically associated with the actual presence of CBD stones. As stated above, ERCP should rarely be utilized as a diagnostic procedure.74

Management of Sod

SOD represents a broad range of symptoms including pain, biliary colic, altered liver function tests, ductal dilation with delayed drainage, and elevated sphincteric pressures. Based on the number of associated symptoms, the response to endoscopic sphincterotomy can be predicted. This disease also has a close association with gallbladder dyskinesia, and may represent a parallel process in that many patients following cholecystectomy for gallbladder dyskinesia will eventually be suspected of also having SOD. While multiple noninvasive tests have been evaluated in this disorder (eg, ultrasonography and scintigraphy), they all appear to lack adequate sensitivity or specificity. The development of endoscopic manometric techniques now allows direct measurement of motility and intraluminal pressures within both the biliary and pancreatic segments of the sphincter of Oddi.75,76

The common thread in patients with this disorder is elevated basal sphincter pressure. Criteria for abnormal manometry include basal pressure >40 mm Hg, peak sphincter pressure >240 mm Hg, >50% retrograde contractions, no relaxation with cholecystokinin administration, and contraction waves >8 per minute. Sphincter of Oddi manometry is technically challenging to perform and carries a high rate of post-ERCP pancreatitis. In addition, any ERCP intervention on patients with suspected SOD is associated with higher rates of postprocedural pancreatitis.75

Management of Acute Cholangitis

Endoscopic biliary drainage has now been clearly shown to be the procedure of choice for patients with acute suppurative cholangitis. In critically ill patients, simple endoscopic stenting or nasobiliary drainage, with or without sphincterotomy, should be performed. Complete clearance of the duct is not necessary as long as drainage had been achieved. Stone extraction can be performed after the patient has stabilized, at the time of stent removal 4–6 weeks later.

Management of Acute Gallstone Pancreatitis

Patients with biliary pancreatitis can typically be managed conservatively, saving ERCP for those patients with worsening pancreatitis or concommittant evidence of biliary obstruction secondary to choledocholithiasis.77 In these cases, early ERCP and sphincterotomy can significantly reduce morbidity and mortality.77,78 The majority of patients who develop gallstone pancreatitis will have spontaneous passage of the CBD stone without intervention. Laparoscopic cholecystectomy should then be performed in the near future to prevent recurrence. Conversely, patients who are not an operative candidate, ERCP and sphincterotomy are effective in minimizing the risks of pancreatitis, but obviously will have no effect on the development of gallbladder complications related to the cholecystolithiasis.

Endoprosthesis Insertion

Currently available endoprostheses or stents vary in their composition, shape, size, length, deployment system, and method of anchorage. The indications for stent insertion include cholangitis, benign/malignant biliary or pancreatic duct stricture, biliary or pancreatic duct leak, retained/unremovable CBD stones, and prophylactic pancreatic duct stent placement for pancreatitis protection.79–82 In patients with biliary fistulae, the goal of the stent is to equilibrate the biliary and duodenal pressures to facilitate closure of the leak (Figs. 3-21 to 3-23).

Initially, a diagnostic cholangiogram or pancreatogram is obtained to identify the lesion's extent and to determine the length of endoprosthesis required, and a guide wire is maintained. If desired, a sphincterotomy can then be performed to facilitate subsequent manipulations, although stent placement can be performed without this maneuver. Ideally, the endoprosthesis will be located with its upper flap above the stricture and its lower flap just outside the papilla, although suprapapillary placement of metal stents is routinely performed for more proximal malignant strictures. Transpapillary positon of plastic stents serves a function to ease removal as well as equilibrating biliary and duodenal pressures in cases of bile duct leaks.

All biliary and pancreatic stents are placed using TTS deployment systems. The diameters of these delivery systems vary based on the type of stent and the actual diameter of the stent. Straight biliary and pancreatic plastic stents come in 3, 4, 5, 7, 10, and 11.5 Fr diameters. For SEMT, a special delivery system is used to insert the stent in a collapsed state (10 Fr diameter). After release, there is shortening of the SEMS as the stent expands to its full diameter (8–10 mm).80,81

Straight plastic biliary stents are temporary and must be changed every 3–6 months.79 Obstructive jaundice and cholangitis are common sequelae of occluded stents. Placing multiple stents may increase the length of overall patency, as bile can traverse around and between the stents even if the stent lumen becomes obstructed. SEMS carry a longer patency rate of 9–12 months as compared to plastic stents.80,81 Uncovered metal stents are less likely to migrate as compared to covered ones, but have a shorter patency rate due to the allowance for ingrowth of tissue or tumor. Newer fully covered self-expanding metal biliary stents also allow for delayed removal, and can therefore be used in the management of chronic benign strictures.

Patients undergoing endoscpic palliation for obstructive jaundice secondary to malignancy who are not operative candidates may be better served with SEMS rather than plastic stents due to the decreased need for repeat endoscopic intervention in patients with a limited life expectancy.80 If patients have both a biliary and duodenal obstruction secondary to malignancy, it is important to place the biliary SEMS prior to the duondenal stent as access to the papilla beomes very challenging.44 Palliation of unresectable malignant biliary obstruction in elderly high-risk patients appears to be one of the most significant indications for biliary endoprostheses (Fig. 3-24).

In addition to biliary disorders, ERCP has been employed in the management of benign and malignant pancreatic disorders. Pancreatic duct stenting can be used successfully to decompress the ductal system, to bypass ductal leaks and strictures, and to treat pancreatic fistulas. Patients with pancreatic divisum may be treated with minor papilla stenting or sphincterotomy. Pancreatic stents are smaller than biliary stents and they contain side holes for drainage. Pancreatic duct stents also can be placed in patients with high risk for post-ERCP pancretitis including SOD, idiopathic/autoimmune pancreatitis, and those having had a complex ERCP with extensive pancreatic or bile duct manipulations (Figs. 3-25 and 3-26).75 Pancreatic duct stents should be endoscopically removed within 2–3 weeks due to the risk of ductal inflammatory changes, whereas biliary stents can be used indefinitely and changed when there is evidence of obstruction. On many occasions, the pancreatic stents will pass spontaneously.

Pancreatic Duct Stones

ERCP for pancreatic ductal stone extraction is technically more challenging and is associated with a higher risk of complications such as pancreatitis. Some clinicians have reported success with the use of mechanical lithotripsy, contact lithotripsy, and/or extracorporeal shock wave lithotripsy to manage pancreaticolithiasis.83 Pancreatic duct stones routinely are harder than biliary cholesterol-based stones and these patients may eventually require surgical intervention.

Endoscopic Pseudocyst Drainage/Necrosectomy

The management of pancreatic pseudocysts and necrotic debri is one of the more recent advances in the therapeutic armamentarium of the endoscopist. Pancreatic pseudocysts can be approached in a transpapillary or a transvisceral fashion based on the location and nature of the pseudocyst. Many pseudocysts have direct connection to the main pancreatic duct, and are referred to as “communicating” pseudocysts. If wire access can be obtained via the pancreatic duct into the cyst cavity, a pancreatic stent can be placed to allow for drainage of the cystic cavity. Although this may result in initial resolution of the cyst, a high recurrence rate exists due to the continued communication to the ductal system. After drainage, subsequent stenting of the pancreatic duct across the site of leakage may be required.

Pancreatic pseudocysts directly adjacent to an endoscopically approachable lumen (ie, stomach, duodenum) may be amenable to a transvisceral approach.84–87 Assuring maturity of the cyst, absence of concern for neoplasm, and no evidence of actual infection are important factors to determine prior to endoscopic drainage. The use of EUS is an invaluable adjunct to this procedure for several reasons.85,87 It can rule out intervening organs or vasculature, determine if there is extensive debri rather than simple fluid collections, and assure proximity of the cyst to the selected viscus. EUS aspiration followed by guide wire placement is followed by tract dilation and eventual pigtail stent placement. Stents are removed in 6–12 weeks after confirming resolution of the pseudocyst.

Patients with pancreatic necrosis rather than simple pseudocyst formation have also been approached endoscopically.88–92 Similar to transvisceral cyst drainage, EUS guidance is used to confirm the presence of a collection of debri, and following tract dilation, the endoscope is advanced directly into the adjacent cavity. Tissue is then removed using a combination of irrigation/suction and snare/basket tissue debridement. Stents are placed to maintain the tract to allow for serial debridement of the necrotic tissue.

Complications of ERCP

Post-ERCP Pancreatitis

The occurrence of ERCP-induced pancreatitis is associated with both procedural factors and patient factors. Although the precise factor leading to postprocedural pancreatitis has yet to be elucidated, many factors including complex interventions including manometry, multiple pancreatic canulations or injections, excess delivery of thermal energy, and placement of covered SEMS have all been implicated. Prophylaxes with antibiotics, steroids, somatostatin, xanthine oxidase inhibitors, and immunologic agents such as IL-1 have been investigated in multiple prospective comparative trials without success in reduction of pancreatitis.74,93 Patient factors associated with pancreatitis include SOD, idiopathic pancreatitis, and the prior history of acute or chronic pancretitis.93 The use of short-term prophylactic pancreatic stent placement may eventually be proven beneficial in patients following higher risk procedures, or who have comorbid disease states increasing their risk for post-ERCP pancreatitis.75

Bacteremia or sepsis following ERCP, similar to pancreatitis, is secondary to procedural factors as well as underlying patient factors.93 Patients undergoing ERCP for obstructive jaundice or cholangitis have a high risk of sepsis if adequate drainage is not obtained. In addition, despite the use of sterile contrast agents, ERCP is a contaminated procedure related to the introduction of duodenal contents and bacteria into the biliary tree during canulation. If contrast is injected above a stricture that cannot be adequately drained, the development of cholangitis uniformly occurs. One method for preventing this is to attempt wire advancement across a stricture first before performing a cholangiogram. In complex strictures, this can be challenging, but it avoids contamination in cases where the stricture cannot be traversed. The performance of biliary dilation also carries a very high risk of bacteremia and prophylactic antibiotics are recommended. Finally, high pressure or high volume injections can also lead to cholangiovenous translocation of bacteria.

Bleeding following endoscopic sphincterotmy occurs in approximately 1% of all cases, and can occur immediately or up to 2 weeks postprocedure. Hemorrhage should be initially managed by repeat endoscopic intervention. Injection sclerotherapy, balloon tamponade, and endoscopic clip placement are the most common and effective ways to manage this complication.94 If unsuccessful, angiographic embolization should be utilized before proceeding to surgical intervention.

Perforation is the least common complication and may occur secondary to the ERCP intervention (wire placement, canulation, sphincterotomy) or the actual advancement of the endoscope. Endoscope-induced perforations can occur at the level of the cervical esophagus due to the blind nature of the initial passage of the side-viewing endoscope, or in the duodenum, usually on the lateral aspect opposite the papilla. Proximal esophageal perforations usually can be managed with antibiotics, NPO status, and cervical drainage as needed. Duodenal perforations secondary to the endoscope may result in a large rent of the lateral wall and may require more aggressive therapy including surgical drainage, or in more serious situations, duodenal diversion techniques.

Perforations secondary to ERCP manipulations may occur in the periampullary duodenum or in the biliary tree. Perforations of the bile duct secondary to guide wires or catheter systems are rare but can result in bile peritonitis. Small perforations and leaks in patients without clinical deterioration can usually be managed with transpapillary stent placement and image-guided peritoneal drain placement as needed. CT scans are vital in the management of these patients.95 Microperforation of the duodenum can lead to extensive retroperitneal, intraperitoneal, mediastinal, and subcutaneous air, which appears very concerning, but as long as the patients are clinically stable, this situation can routinely be managed conservatively with antibiotics, NPO status, and close observation. Conversely, patients identified to have retroperitoneal or intraperitoneal fluid collections will most likely require aggressive drainage via either surgical or image-guided techniques. Emergent resective therapy (pancreaticoduodenectomy) should be avoided in these situations.

The small bowel up until recently had been an elusive part of the gastrointestinal tract in terms of diagnostic and therapeutic endoscopic intervention. The advent of capsule endoscopy has permitted the endoscopist to obtain recorded images of the lumen of the small bowel for identification of obscure sites of bleeding, inflammatory changes, and neoplasia. Unlike contrast studies such as enteroclysis, capsule endoscopy simulated the visual advantages of flexible endoscopy, and with the time recording and navigation system, was able to approximate the actual site of the identified disease. Unfortunately, there was no potential for tissue sampling or providing therapy. This deficiency has now been addressed with the progression of deep bowel enteroscopy.

Previous endoscopic approaches to evaluate the small bowel included Sonde enteroscopy and push enteroscopy. Both of these were very challenging, time consuming, often unsuccessful, and provided limited alternatives for therapy. Intraoperative enteroscopy, either transoral or transanal, allowed for the manual pleating of the small bowel on the enteroscope, but was also very challenging.96 Therapy would be provided surgically after the offending site was identified endoscopically. Intraoperative endoscopic evaluation of the small bowel can also be performed via an enterotomy in the midportion of the bowel allowing the endoscope to be advanced both proximally and distally. One of the undesired consequences of intraoperative endoscopy is massive bowel distention. The use of CO2 insufflation rather than air insufflation has been shown to minimize the overall distention and length of time for resolution of this problem. Many endoscopists are looking to use CO2 for all endoscopic interventions, especially those that are expected to be of longer duration.

Over the past 10 years, several new endoscopic systems have been developed and utilized for the evaluation and treatment of small bowel disease. Double balloon endsocopy (DBE) and single balloon endoscopy (SBE) have allowed the endoscopist to fully evaluate the small bowel, obtain tissue samples, and provide therapy for processes such as bleeding, obstruction, and occult neoplasia.97–105 In addition, patients following surgical resection and reconstruction (ie, Roux-en-Y bypass, long afferent limb), balloon enteroscopy can allow access into the desired segment of the small bowel.102

Both systems utilize the principle of scope fixation with a soft balloon that is serially inflated and deflated as the scope is advanced. This permits the endoscopist to pleat the bowel over the endoscope. This is perfomed both antegrade and retrograde to visualize the entire mucosal surface of the small bowel, and can also be used for evaluation of the entire colon following unsuccessful standard colonoscopy.104 Unique overtubes are also available for deep bowel enteroscopy, and are used in conjunction with the endoscopes.101,103 As these techniques can be somewhat time consuming (1–4 hours), it is not uncommon to perform these under general anesthesia. The use of fluoroscopy is also helpful in guiding the endsocopist through the small bowel.

The field of therapeutic lower endoscopy originated in 1975 when Shinya and Wolff reported the first series of colonoscopic polypectomies.106 This groundbreaking report transformed colonoscopy from a purely diagnostic tool into an interventional modality. Since then, therapeutic colonoscopy has expanded to include resection of large neoplastic lesions, stenting for management of leaks, strictures, fistulae and obstructions, and bleeding. Advances in instrumentation and technique will continue to broaden the applications of interventional colonoscopy, possibly even using the colon as a portal to the peritoneal cavity.

Indications

Screening colonoscopy has become the standard of care for evaluation of average risk patients over the age of 50.107–110 Prior screening tools such as fecal occult blood testing, sigmoidoscoy, and digital rectal exams no longer are considered as effective screening tools.111 CT colonography, however, has gained some support due to improved abilities to identify colonic neoplasia; however, smaller lesions are still somewhat a challenge for this imaging tool. The indications for colonoscopy are listed in Table 3-3.

Contraindications

The contraindications for colonoscopy are in part similar to those for EGD, and are related to the patient's associated comorbidities, underlying gastrointestinal disorders, or patient's inability to tolerate conscious sedation. As with EGD, recent myocardial infarction, pneumonia, and recent foregut surgical procedure are relative contraindications for colonoscopy, and the risks and benefits need to be weighed on an independent basis for each patient to determine appropriateness. A recent surgical anastomosis is most likely safe at any time during the postoperative period to be evaluated endoscopically, remembering that tissue strength will be weakest on postoperative day's five to seven.

Coagulopathy secondary to thrombocytopenia, liver failure, renal failure, or exogenous use of anticoagulants and platelet-inhibiting agents is a relative contraindication for a diagnostic colonoscopy, but an absolute contraindication for a therapeutic intervention. Patient noncooperation or an inability for a patient to be safely sedated due to high cardiopulmonary risk is also contraindication to colonoscopy. Respiratory depression secondary to medications as well as inability to maintain an airway can occur in these high-risk patients even though there is no transorally placed scope. Preassessment with ASA classification and Malampatti scores will help predict this high-risk group.16 Patients with suspected perforation, ischemic colitis, acute diverticulitis, or toxic megacolon should not undergo colonoscopy unless there are plans to provide immediate therapy such as endoscopic closure or stent placement, or surgical intervention.

Patient Preparation

Most endoscopic evaluations of the lower gastrointestinal tract can be done under conscious sedation on an outpatient basis. Unsedated colonoscopy can be performed safely but requires a compliant, nonanxious patient, who understands that prior abdominal surgery as well as female gender increases the need for conversion to sedated endoscopy.

The day before the examination the patient should begin a light diet with only clear liquids at lunch. The most common bowel preparation for colonoscopy utilizes a sodium sulfate–based electrolyte solution containing polyethylene glycol as an osmotic agent (eg, GoLYTELY). Alternative regimens including magnesium citrate and multiple enema solutions have also been described. In addition to different agents for prep, endoscopists have also utilized varied timing for preps with the use of split doses, with the final dose being given four hours before the scheduled procedure. Fleet Phospho-soda, a small volume prep, is no longer an alternative due to the rare occurrence of cardiac complications.

Prophylactic antibiotics are usually not required for colonoscopy. Although diagnostic procedures can be performed in patients on anticoagulative therapy, these medications should be withdrawn if polypectomy or other therapeutic procedures are expected to be performed. Aspirin therapy, unlike other anticoagulative medications, probably does not alter the risk of postpolypectomy bleeding.

Basic Endoscopic Techniques—Colonoscopy

When performing colonoscopy, there are several universal principles to the technique similar to upper endoscopy, but there are also several specific caveats to assure performance of a safe procedure. Due to the tortuosity of the colon and the lack of fixation, manipulations such as scope torquing, loop reduction, patient position changes, and abdominal wall manual pressure are vital to the performance of colonoscopy. One other difference from upper endoscopy is the lack of reliability of correlation of shaft length inserted and actual anatomic position in the colon. Therefore, understanding specific colonoscopic landmarks is very important to interpreting actual lower gastrointestinal anatomy. In addition, surgical alterations to the anatomy must be recognizable (Fig. 3-27).

A digital rectal examination should always be performed prior to initiating the colonoscopic exam. This provides lubrication of the anal canal, relaxes the anal sphincters, provides evaluation of the prostate and lower rectal vault, and assesses the patient's level of sedation. The endoscope is introduced either by direct straight insertion or by rubbing the tip of the endoscope along the perineal body with the right index finger. Once reaching the anal verge, the tip of the endoscope is directed into the anal canal.

Once in the rectal vault, insufflation is initiated to allow view of the lumen. Although mucosal inspection occurs during advancement, principal evaluation for pathology occurs on scope withdrawal after the cecum is reached. Gentle advancement of the colonoscope is now performed. If the lumen is lost to view, termed a “red out,” the scope is slightly pulled back and the wheels deflected in combination with scope torque to reestablish the lumen. Passage of the scope into the sigmoid colon can be challenging in patients with prior abdominal surgery, morbid obesity and a large pannus, or multiple diverticuli (Fig. 3-28). Abdominal compression and patient position change to supine may assist in this maneuver. Rarely, a “slide-by” maneuver is required to overcome the tight angulation in and out of the sigmoid colon. This technique entails careful insertion without complete luminal view but with appearance of the mucosa sliding by the scope. During all portions of the colonoscopy, however, increased patient discomfort, “redded out view,” and excessive scope resistance with advancement are markers to the endoscopist to pull back one's colonoscope.

Exiting the sigmoid colon may require building up a “loop.” This may lead to increased patient discomfort and may require additional medication. Once access into the descending colon is achieved, the loop is reduced by gentle withdrawl and slight torquing of the scope. Adding variable stiffness to the scope, if available, will now allow advancement in a one-to-one fashion, to the splenic flexure. “One-to-one” refers to equal scope tip advancement with scope insertion. The descending colon is usually quite straight, and the splenic flexure is identified by the extraluminal blue hue as well as the tight turn encountered as one enters into the distal transverse colon. Suctioning and scope withdrawal will assist in maintaining positioning beyond the splenic flexure.

Introduction of the scope, again with the addition of variable stiffness, should allow one-to-one progress through the transverse colon, which is easily identified by the triangular configuration. As one proceeds toward the hepatic flexure, the blue hue of the liver becomes apparent. At this time, paradoxical motion routinely will occur with scope introduction. Access into the ascending colon usually requires the endoscopist to make a sharp deflection at the hepatic flexure followed by withdrawal of the scope and simultaneous suctioning. The ascending colon may have a yellow discoloration due to the continued passage of succus entericus despite a complete bowel preparation. Asking the patient to take a deep breath as well as placing them in supine position may assist in this maneuver. Eventually, the cecum is identified by the ileocecal valve, appendiceal orifice, cecal strap, abdominal wall transillumination, and right lower quadrant palpation (Figs. 3-29 and 3-30). Intubation of the ileum, however, is the only way to confirm 100% that you have actually reached the cecum. The terminal ileum can be intubated by deflecting the tip toward the ileocecal valve, gently withdrawing the scope, and prying open the upper lip of the valve. Throughout this maneuver, air insufflation is used. The scope is then slowly advanced into the terminal ileum.

The goal of the endoscopist is to reliably and safely gain access into the cecum, confirming one's position, and then performing a slow careful withdrawal evaluating the entire mucosal surface. Areas of excess stool must be flushed clear and extra care must be taken at the flexures and around larger folds to investigate for underlying disease. Retroflexion of the endoscope, which had been utilized for evaluation of the rectal vault, is now being performed with some regularity, in the cecum and flexures, as well as to see behind larger folds. Manipulation by patient position change, as with upper endoscpy, may aid in visualization of areas with excess stool. Retroflexion in the rectum can be done at the beginning or at the end of the procedure (Fig. 3-31). The colonoscope is withdrawn into the anal canal and then carefully advanced for several centimeters. Full upward deflection along with clockwise torquing and gentle advancement will result in the scope looking back toward the distal rectum and dentate line.

Complications

Complications specifically related to colonoscopy include hemorrhage and perforation. The former is most unusual following diagnostic colonoscopy, occurring in 0–0.07% of cases. Hemorrhage in this setting is usually intra-abdominal such as following injury to the colon mesentery or to the capsule of the spleen, resulting from the use of excessive force during manipulation. Hemorrhage is seen more often following polypectomy (1–3%).112 Postpolypectomy bleeding can be immediate or delayed, and can occur up to 2 weeks after the procedure. Repeat colonoscopy is recommended for hemodynamic instability, transfusion requirement, and continued or recurrent episodes of bleeding.

Perforation is the most common complication of colonoscopy, occurring in <1% of cases.111 These injuries are caused by mechanical or pneumatic pressure and are most common at the rectosigmoid or sigmoid–descending colon junctions along the antimesenteric border at the site of scope looping. Alternatively, cecal perforation can occur if the colon is excessively insufflated across a more distal nontraversable obstruction. In patients with a competent ileocecal valve, there is a resultant trapping of air between the distal obstruction and the valve, which prevents release of the insufflated air into the small bowel.

Therapeutic colonoscopy can also be complicated by perforation, at the site of therapy, as well as the other previously reported sites. Reported incidences are rare (<1%), with the greatest risks occurring with the removal of sessile polyps. Following polypectomy, patients occasionally develop localized pain secondary to peritoneal irritation, along with fever, tachycardia, and leukocytosis. There is usually no evidence of diffuse peritonitis or overt perforation (ie, no “free air”). This syndrome has been labeled postpolypectomy syndrome, and is probably attributable to a transmural electrocoagulation injury with microperforation. Patients usually can be managed conservatively with antibiotics, analgesics, and close observation with serial exams. Symptoms usually resolve within 48–72 hours and rarely are surgical interventions needed.

In patients with a suspected perforation, CT studies are recommended to evaluate for abscess formation or intra-abdominal fluid collections. Intra-abdominal fluid collection is a more concerning finding and these patients require close observation with a low tolerance for surgical intervention. It is important to base therapy on individual patient status, however, rather than just radiographic studies. The presence of intraperitoneal or retroperitoneal air in the absence of clinical peritonitis or hemodynamic instability does not warrant surgical exploration.

Polypectomy

By far, the most commonly performed colonoscopic intervention is polypectomy. When performed at regular intervals, removing adenomatous polyps has been shown to significantly reduce the incidence of colon cancer.107 Small sessile lesions are amenable to hot or cold biopsy polypectomy. For hot polypectomy, standard biopsy forceps without spike are attached to an electrocautery unit set at 10 to 20 watts. The polyp is grasped and lifted from the surrounding mucosa, and monopolar cautery is applied in short bursts until the base of the polyp whitens. The biopsy forceps is sharply withdrawn and the polyp is then removed through the working channel of the colonoscope. Polypectomy serves to biopsy the polyp and ablate any residual tissue, thereby diminishing the risk of progression to carcinoma. Due to the concern for delayed bleeding following sloughing of the eschar as well as the risk of perforation, many endoscopists are now adopting cold polypectomy techniques. Several series have shown no difference in the rates of bleeding, and it presents a more easily evaluable specimen to the pathologist without cautery artifact.

Pedunculated polyps are suitable for snare polypectomy (Fig. 3-32). The base of the polyp is encircled with the snare several millimeters below the head-stalk junction. This allows removal of a portion of the stalk for pathologic evaluation to rule out invasion of the lamina or muscular layers, identifying a more advanced neoplasm. Cautery is applied as the snare is gradually closed, thus severing the polyp and cauterizing the base. Broader-based pedunculated polyps may be managed with placement of an endoscopic pretied endoloop proximal to the site of resection to help minimize bleeding. These loops usually will slough off within several weeks and pass spontaneously.

Sessile polyps are frequently more difficult to manage than pedunculated polyps. Small sessile lesions may be captured in a single application of a snare and resected, with (hot) or without (cold) cautery, while larger lesions might require resection in a piecemeal fashion. Piecemeal resection provides for removal of a larger lesion along with ablation of residual tissue, but may make pathologic interpretation more challenging.113

Resection of sessile polyps poses a higher risk of colonic perforation than pedunculated polyps. Given that, endoscopic mucosal resection has been developed to minimize the risk of perforation and ensure complete resection of the lesion. This is provided by submucosal injection of saline to create a cushion between the mucosa and muscularis, to help minimize the risk for perforation.113–116 Lesions that do not easily elevate may have a component of invasisve carcinoma and these tumors should be biopsied and tattooed, rather than attempted to be endoscopically resected. Following removal of large sessile lesions, APC ablation of the site has been proposed to minimize adenoma recurrence.

Polyp Retrieval

Small polyps may be retrieved through the suction channel of the endoscope and captured in a trap. Larger polyps may be recovered in a net placed through the working channel of the endoscope or apposed to the tip of the endoscope by constant application of suction and then withdrawn with the scope. Marking the site of resection with a carbon particle–based tattoo via a sclerotherapy needle will allow for more accurate surveillance, as well as to guide surgery if the polyp proves to be malignant. Injections should be placed at multiple sites circumferentially to allow for the most reliable visualization at the time of surgery or during subsequent surveillance endoscopy.

Polyp Surveillance

Over the past 15 years, much has been learned about the nature of the adenoma carcinoma sequence, leading to ongoing changes in the recommendations for polyp surveillance. Average risk patients with satisfactory bowel preps require repeat surveillance in 10 years, while patients with those with poorer preps might be recommened to have a shorter interval of 5 to 7 years.107,109–111 Hyperplastic polyps carry an undetermined risk/association with advanced neoplasia, although there has been some suggestion that left-side hyperplastic lesions have a more aggressive nature than those in the rectosigmoid. Similar to fundic gland polyps of the stomach, these lesions may be sampled but do not need to be fully removed. Tubular adenomas, tubulovillous adenomas, and villous adenomas warrant a surveillance colonoscopy at 5, 3, and 1 year, respectively.107

Lower Gastrointestinal Bleeding

Sources of lower gastrointestinal bleeding include UGI bleeding, infection, ischemia, neoplasia, diverticulosis, angiodysplasia, and anorectal disease. A detailed history of the nature of bleeding is vital to the management of patients with lower gastrointestinal bleeding identifying underlying coagulopathy, recent surgical or colonoscopic interventions (polypectomy), and associated comorbid diseases. These factors are important in patient management and guiding surgical and nonsurgical interventions.

The role of bowel preparation prior to colonoscopy in the face of lower gastrointestinal bleeding is dependent on the rapidity of the bleeding. As blood is a very active cathartic, colonoscopy can be performed in the unprepped colon with extensive bleeding.117–119 Otherwise, a rapid prep over 3 to 4 hours can be utilized in patients with less aggressive bleeding prior to endoscopic evaluation. The endoscopist must compare the need for a more urgent intervention versus the necessity of a more adequately cleared mucosal surface. In addition, newer irrigation devices are now available that can be affixed to the colonoscope to provide for high pressue and volume irrigation and cleaning.

Colonoscopic therapy for lower gastrointestinal hemorrhage within 6 to 24 hours of admission has been shown to diminish rates of rebleeding and reduce the necessity for urgent surgical intervention.117 Various methods are available for hemostasis including thermal and nonthermal devices, and are described in the preceding sections of this chapter. One must always remember, however, that the colon wall is thinner, especially on the right side, as compared to the stomach. Depth of penetration of the varied thermal endoscopic devices must be closely considered to avoid full thickness perforations.

Diverticular disease is the most frequent cause of lower gastrointestinal hemorrhage. Up to 75% of diverticular bleeds are self-limited, but in those patients with transfusion requirements, massive hematochezia, or hemodynamic instability, colonoscopy may aid in confirming diagnosis, identifying the site, achieving hemostasis and limiting patient morbidity.117–121 Locating the precise site of bleeding may be difficult in the face of multiple diverticula and a blood-stained colon. The bleeding diverticular vessel is frequently at the lip of the diverticulum, although bleeding vessels in the dome of the diverticulum may also occur. The use of endoscopic clips and ligation bands for treatment of bleeding diverticuli has also been reported.120,121

Vascular ectasia or angiodyspoasia, commonly in the right colon but also routinely multicentric, is another common cause of lower gastrointestinal hemorrhage. Argon plasma coagulation is invaluable in this situation, but care should be taken to avoid excessive distension of the bowel, as the argon gas accumulates and could lead to perforation.122 Other thermal endoscopic contact probes, as described in previous sections of this chapter, can also be utilized.

Colonoscopic Decompression

Mechanical or nonmechanical obstructions with unrelieved distention of the colon, in addition to leading to patient discomfort, can result in bowel ischemia, perforation, and death. In patients with colonic distention secondary to acute pseudo-obstruction, Ogilvie's syndrome, colonoscopy provides both a diagnostic and therapeutic potential. Underlying etiologies including ischemia, infectious colitis, or an unsuspected obstructing lesion must be excluded.

Conservative treatment is initially indicated in patients with benign abdominal exams, clinical stability, and cecal diameters less than 12 cm. Patients should be maintained NPO, electrolyte imbalances corrected, narcotics withdrawn, and one should consider possible placement of nasogastric and rectal tubes.

Colonoscopic decompression is done without a routine bowel preparation, thus limiting the overall mucosal evaluation. The endoscope is advanced, with limited air insufflation, as far proximally as can be achieved without excessive bowel wall tension, minimizing any risk for perforation. Decompression is then performed upon withdrawal of the colonoscope, suctioning both fluid and intraluminal air. Although the cecum is the optimal endpoint, successful decompression can also be achieved with a less complete colonoscopy. Evaluation of visualized segments of the colon for ischemia and/or mechanical obstruction, possibly requiring stent placement or dilation, is crucial. It must be understood that repeat colonoscopic decompression is routinely required in patients with pseudo-obstruction, and they should be watched closely for several days.

Enteral Stents

Colonic stenting can provide relief of malignant colon obstruction or benign stricture and serve either as palliation or as a bridge to operation.123–127 Permanent SEMT are commonly employed in large bowel obstruction. Through-the-scope stents are placed under endoscopic and fluoroscopic guidance. The malignant stricture is located endoscopically and a guide wire is passed through the narrowed lumen (Figs. 3-33 and 3-34). Contrast is injected into the bowel lumen, typically through an ERCP catheter, to define the borders of the stricture. If possible, the proximal and distal extents of the stricture are marked by injecting submucosal contrast. The stent is then placed over the wire, positioned properly, and deployed (Fig. 3-35). Self-expanding metal stents have shown efficacy in reducing the need for emergency operation in acute large bowel obstruction.123,124,126 In patients who are not candidates for operation, metal stents may serve a palliative purpose.125 Stenting is generally safe, although perforation has been reported in up to 10% of cases. Migration of stents can also occur, although is less likely due to tissue in-growth, which can also lead to subsequent stent occlusion.

Endoscopic ultrasound has become a mainstay in the diagnostic and therapeutic armamentarium of endoscopy (Table 3-4). The staging of neoplastic processes throughout the gastrointestinal tract, and those structures adjacent to the hollow viscera, can now be more accurately accomplished, with the addition of tissue sampling for confirmation of disease.128–130 The use of neoadjuvant therapy has become closely tied to the results of endoscopic ultrasonographic findings, providing for more appropriate patient care. Finally, directed therapy for endoscopic removal, drainage, and palliation of gastrointestinal and extragastrointestinal diseases is now readily being performed with the assistance of EUS.131

The echoscope endoscopically visualizes similar to a side-viewing duodenoscope. After providing appropriate sedation, endoscopic visualization is used initially to achieve appropriate scope position. Once the endoscope is in the desired position, a balloon on the endoscope tip is filled with deaerated water. The lumen of the GI tract is suctioned to affix the scope adjacent to the mucosal surface as excess air limits ultrasound views. Miniature probes as well as Doppler capabilities are also available. When a lesion is found, the working port of the scope allows for passage of a 19 or 20 gauge needle to obtain fine-needle aspiration biopsies. Immediate cytologic evaluation is recommended as repeat passes for further samples is commonly required.

The future developments in endoscopy will be based on advancements of both the tools and the applications available to endoluminal therapy. As surgery becomes less invasive with the advancement of laparoscopy, endoscopy is taking on an increasingly more invasive and therapeutic role. Intraluminal and translumenal procedures are being developed with the goal of further supplanting surgery. Recent interest in NOTES united surgeons and gastroenterologists with the desire to access the abdominal cavity via naturally existing orifices including the stomach, colon, bladder, and vagina. Using existing endoscopic technology, investigators have attempted numerous intra-abdominal procedures in porcine models, and eventually human cases under laparoscopic guidance have also been reported.132,133 An appropriate application for this approach is still yet to be elucidated. It is theorized that NOTES may have distinct advantages over laparoscopy in that it may not necessarily require a sterile working environment to perform, and it possibly could also be completed under conscious sedation similar to other endoscopic procedures.134,135

The obvious limitations to NOTES were based on the lack of adequate and appropriate endoscopic equipment. The accessories were too flimsy to perform intra-abdominal manipulation of tissue, and the endoscopes were too flexible, inhibiting access and stable positioning once in the abdominal cavity. It was apparent early on that stable platforms would be necessary as well as endoscopic tools for cutting, hemostasis, and tissue manipulation. Transoral and transvaginal multichannel platforms with internal capability for manipulation and fixation are now becoming available. Scissors, suturing devices, bipolar forceps, and grasping devices are a few of the novel instruments soon to be added to the endoscopist's armamentarium.

These tools, however, will have a more likely impact on intraluminal endoscopic surgery.136 The ability to perform full thickness resection, intraluminal anastomoses, and closure of perforations are all likely procedures to be seen in the very near future, and it is imperative that surgeons stay abreast of the numerous advancements in these technologies.