Chapter 11. Retrograde Instrumentation of the Urinary Tract

The ability to manipulate the urinary tract without the need for an open surgical incision differentiates urology from other disciplines. Such intervention may be required for diagnostic or therapeutic purposes (or both). Understanding the various catheters, guidewires, stents, endoscopes, and associated instrumentation is key in helping physicians accomplish their desired tasks. Manipulation of the urinary tract should be performed in a gentle fashion; instruments need not be forced. An understanding of anatomy and alternative instrumentation should allow physicians to accomplish their tasks with finesse. The patient should understand the proposed procedure and potential complications. For example, the attempt to place a retrograde ureteral catheter to drain an infected kidney may ultimately lead to a percutaneous nephrostomy if the surgeon is unable to achieve retrograde drainage. Knowing when to stop is as important as knowing when to start.

Many procedures are performed at the bedside or in a cystoscopy suite under local anesthesia. A patient who is comfortable, informed, and assured will more likely cooperate and tolerate the procedure. A physician who is familiar with the proposed instrumentation and understands its limitations and alternatives will win the patient's confidence.

Manipulation of the urinary tract can result in significant injury. Anticipated prolonged procedures should be covered with appropriate antibiotics directed by preoperative urine cultures and sensitivities. Generous use of a water-soluble lubricant and low-pressure irrigation decreases the likelihood of significant iatrogenic infections. Patient positioning is as important as proper choice of instrumentation. Pressure points must be identified and adequately padded, especially when the patient is placed in the dorsal lithotomy position. In addition, the legs should be secured in their stirrups to prevent accidental injury, such as those that might result from a leg hitting the surgeon after an unexpected obturator reflex during endoelectric surgery.

Urethral catheterization is the most frequent retrograde manipulation performed on the urinary tract. Catheters are placed to drain the bladder during and after surgical procedures requiring anesthetics, to assess urinary output in critically ill patients, to collect reliable urine specimens, for urodynamic evaluation, for radiographic studies (eg, cystograms), and to assess residual urine. Such catheters can be left indwelling with a self-retaining balloon, as is done with a Foley catheter. An in-and-out procedure to drain a bladder does not require a self-retaining device. Adequate lubrication and sufficient frequency to keep the bladder at reasonable volumes are critical and must be emphasized to the patient performing self-intermittent catheterization; sterility is secondary. In contrast, when a catheter is left indwelling it is important to use sterile technique.

Technique of Catheterization

In Men

The penis should be positioned pointing toward the umbilicus to decrease the acute angulation as the catheter traverses the bulbar urethra. On most occasions, the catheter passes without difficulty. When difficulties arise, a careful history relating to previous urologic manipulations is critical. Strictures are not infrequent and can occur after endourologic surgery. Urethral strictures can be found from the meatus to the bladder neck. History of a straddle injury may suggest a bulbar urethral stricture. Adequate lubrication injected into the urethra and instruction of the patient to relax his pelvic floor eases the passage beyond the striated rhabdosphincter. A large-caliber catheter of approximately 18F should be used. Narrow, stiff, small catheters have greater potential of creating false passages and possible perforation. Coudé (elbowed) tipped catheters frequently help negotiate a high bladder neck, as seen with benign prostatic hyperplasia. With self-retaining Foley catheters, complete advancement until the elbowed valve is at the meatus or until the urine returns is important. Inflating the balloon prematurely (while it is in the urethra) may result in severe pain and possible urethral rupture. This must be emphasized to ancillary nursing personnel dealing with patients who are unable to communicate effectively, because under such circumstances, urethral rupture may present only after severe infection is evident.

In Women

It may be difficult to identify the meatus, especially in patients with obesity or hypospadias. Lateral and outward traction on the labia and the use of the posterior bill of a vaginal speculum may be helpful. With adequate instruction and a mirror to visualize the meatus, women can learn to catheterize themselves. For repeat catheterizations, a finger inserted into the vagina can help to guide the catheter.

Difficult Placement and Removal

When a urethral catheter cannot be placed, filiforms and followers may be used. The narrow filiform leaders are stiff and can puncture the urethra if too much force is used. Thus, gentle advancement should stop when resistance is encountered, and the initial filiform should be left in place. A second and third filiform, and possibly additional ones, should be placed next to the previously placed catheters in hope that the existing catheter occupies false passages or tortuous kinks. Eventually, one of the filiforms should pass and coil into the bladder. A screw adaptor at the end of the filiform can be used to connect progressively larger followers to dilate the narrowed urethra. After adequate dilatation, an open-tipped Council catheter can be placed over the filiform and into the bladder. If a problem or undue resistance is encountered at any stage, the procedure should be aborted and a suprapubic cystostomy should be placed to achieve adequate drainage.

Indwelling catheters should be secured to a closed gravity drainage system. Drainage tubing connected to catheters should be positioned to limit dependent curls and thereby limit airlocks that will frequently limit bladder evacuation. For long-term requirements in males, the catheter should be secured to the abdominal wall to decrease urethral traction pressure and potential stricture formation. Meatal care is needed to ensure adequate egress of urethral secretions.

Difficulty is much less common when removing indwelling urethral catheters. Here, the retention balloon is deflated prior to removal. On occasion, the balloon may not deflate. Inspection of the valve frequently reveals a problem. One may cut proximal to the valve in hopes of evacuating the balloon contents, but this is not always successful. Other options include transperineal or transabdominal balloon puncture (best with ultrasonographic guidance), or injection of an organic agent such as ether through the balloon port (with a full bladder to prevent chemical cystitis) to dissolve the balloon wall. If the catheter cannot be advanced, retracted, or twisted, one should suspect an unintended suture that could have been placed during prior surgery; such sutures can be cut via the small pediatric endoscope placed along the Foley catheter. Another complication of urethral catheters is incrustation, especially when a catheter is left indwelling for a long time.

Catheter Design

Catheters differ in size, shape, type of material, number of lumens, and type of retaining mechanism (Figure 11–1). Standard sizes of external catheter diameters and most endoscopic instruments are given according to Charriére's French scale (units of 0.33 mm = 1 French [F] or 1 Charriére [Charr]). Thus, 3F equals 1 mm in diameter and 30F equals 10 mm in diameter.

The choice of catheter size is dependent on the patient and the purpose. Large-caliber catheters are used to evacuate blood clots or other debris. Other catheters are used to stabilize grafts after open urethroplasties, for stenting after endoscopic incisions of strictures, for support of external ureteral catheters, or to assess urinary output. Triple-lumen catheters (one port for balloon inflation and deflation, and one each for inflow and outflow) have smaller lumens than two-way catheters. Other catheter variables include balloon size and construction materials; smaller catheters typically have smaller balloons. Large balloons (eg, 30 mL) can be inflated well over 50 mL to decrease the likelihood of the balloon migrating into the prostatic fossa, especially after transurethral resection of the prostate (TURP). They can be used as traction devices against the bladder neck to control hemorrhage from the prostatic fossa after TURP.

The rigidity of the catheter, the ratio between internal and external diameters, and the biocompatibility depend on the material with which the catheter is made. The standard latex catheter can result in severe reactions in patients with latex allergies, most commonly seen in those with myelomeningoceles. Silicone varieties are good alternatives in such situations. Mucosal irritation is decreased when catheters with a low coefficient of friction are used. Hydromers are placed onto catheters to allow for transient coating, creating an interface between biologic tissues and the foreign catheter; this interface lasts for approximately 5 days. Permanent hydrogel coatings last the life of the catheter. Decreasing the coefficient of friction of these catheters brings about a decrease in mucosal irritation and better biocompatibility. Catheters with a longer lasting interface result in decreased incrustation.

To identify and aid in treating urethral pathology, endoscopic inspection via a urethroscope with a 0° lens is helpful. Stricture disease can be identified or confirmed after radiographic studies. Strictures are characterized by circumferential narrowing. Sequential dilation of urethral strictures by inserting catheters of increasing size exerts shear and tear forces to the mucosa and is likely to produce extended scarring. Thus, stricture recurrence is common if periodic urethral dilation is terminated. Balloon dilation of a stricture with 7–9F balloon dilators (which can be passed over guidewires and inflated up to 30F with pressures of up to 15 atm) does not exert shear force, but the long-term results are varied. Limited circumferential strictures can be incised under direct vision with an endoscopic cold knife. The incision is usually made at the 12-o'clock position, adequate to allow passage of the urethroscope. The bladder then can be evacuated and adequate irrigation used if further incision results in hemorrhage. It is difficult to identify the true extent and depth of a stricture solely by vision because scarring can involve deeper tissues. Here, urethral ultrasonography is an adjunct.

Urethral diverticulum can be identified with urethroscopy. A catheter can be placed through the neck of the diverticulum to help confirm its location during definitive open surgical repair. Urethroscopy can be used to direct injection of dye into rare retained müllerian duct cysts, to identify and extract foreign bodies or rare calculi, and to access biopsy-suspicious lesions. Urethroscopy allows endoscopic treatment of urethral condylomata.

Endoscopic inspection of the lower urinary tract requires irrigation, illumination (fiberoptics), and optics. The optics and illumination are offset by the irrigating and working port. To optimize a complete examination, the rigid endoscope should be rotated, and 0°, 30°, 70°, and 120° lenses may be required. Suprapubic pressure facilitates inspection of the bladder dome, which frequently has an air bubble. A systematic approach is required when evaluating the urethra, prostate, bladder walls, dome and neck, and ureteral orifices (including location, number, shape, and character of efflux). The bladder should be evaluated at different levels of filling. It is only after full distention of the bladder that characteristic glomerulations and ecchymoses are seen in patients with interstitial cystitis. Rectal examination with the endoscope in place is informative, especially in assessing prostate size and length of prostatic urethra. Similarly, concurrent vaginal examination in women can be useful in evaluation of cystoceles.

Choice of irrigant during endoscopic manipulation is important. There are conductive and nonconductive irrigants. Conductive irrigants, which include saline and lactated Ringer's solution, would be inappropriate during traditional endoelectric surgery because the electrical charge would be diffused by the irrigant. Nonconductive irrigants include water and glycine. Water has a theoretic advantage of increasing visibility, and because it is hypotonic, it can lyse tumor cells. If the potential exists for increased intravascular absorption, iso-osmotic or other nonhemolyzing agents are preferred to hypotonic solutions.

Rigid endoscopy results in discomfort, which can be minimized with 1% lidocaine per urethra as a local anesthetic. Flexible endoscopes decrease patient discomfort and allow for instrumentation in the supine rather than the dorsal lithotomy position. They are now used routinely in an office setting for hematuria/tumor surveillance and double-J stent retrieval. Videoendoscopy with flexible scopes allows patients to visualize normal and abnormal anatomy and thus helps them understand their pathology. Videoendoscopy reduces fluid contact to the urologist and can help reduce potential cervical neck disease exacerbated with altered posture when endoscopy is performed without videoendoscopic monitoring. However, there are disadvantages. Flexible scopes have smaller irrigating ports, and they do not have a working sheath. As a result, changing lenses, assessing residual urine, and repeat evacuation of irrigant cannot be completed without entirely removing the endoscope. Rigid endoscopy allows for a greater variety of instrumentation, better optics, and increased durability.

Instrumentation similar to that used to evaluate the urethra and bladder can be used to inspect continent urinary reservoirs or conventional ileal loops. A Robinson or a Foley catheter placed prior to the endoscope gives the operator a visual landmark and an exit port for irrigation to keep the procedure at a low pressure. Alternatively, the Foley balloon can be inflated and the catheter plugged to transiently expand the intestinal segment in hopes of helping to identify landmarks or pathologic lesions. Endoscopic inspection allows for identification of calculi, foreign bodies and mucous plugs, and also has the potential for intubation of ureterointestinal anastomoses.

Ureteral catheterization is required in performing retrograde pyelography, collecting urine for cytologic examination or cultures, and performing brush biopsies (Figure 11–2). Other procedures (Figure 11–3) that require ureteral catheterization include draining an obstructed kidney due to either intrinsic or extrinsic compressions and placement of an internal double-J stent. Finding the ureteral orifice can be difficult. Long-term indwelling Foley catheters, infection, history of ureteral reimplantation, or renal transplantation can hinder identification of the ureteral orifice. One must first try to identify the interureteric ridge and then look for a jet of urinary efflux. Varying bladder volumes and use of intravenous methylene blue may be helpful. However, it may take up to 5–20 minutes for intravenous agents to be excreted out of the ureteral orifice. Once the orifice is identified, catheters usually are placed uneventfully. However, in the setting of benign prostatic hyperplasia with J-hooking of the distal ureter, previous retroperitoneal surgery, reimplantation of the ureter, decreased lower extremity mobility or other skeletal abnormalities, or edema or kinking secondary to long-standing impacted ureteral calculi, catheterization procedures can be difficult or impossible. An Albiron bridge may help direct catheters and guidewires.

There are many configurations of catheter tips (Figure 11–4). Acorn or cone-tipped catheters are excellent for routine retrograde pyelography. Care should be taken to eliminate air in the catheter before injection to avoid confusing air with a filling defect. Fluoroscopy helps determine the appropriate volume of radiocontrast material to decrease the likelihood of pyelolymphatic or pyelovenous reflux or forniceal rupture. The average collecting system holds 7–9 mL of contrast material. If performed under local anesthesia, overdistention is recognized by severe ipsilateral flank pain. With low-pressure injections, there is no systemic absorption of contrast material. A Coudé-tipped catheter allows for dramatic mobility of the tip of the catheter by merely twisting it; there is no need for exaggerated motion of the endoscope. This is helpful in orifices that are difficult to identify because of edema or tumor infiltration.

To bypass severe angulations, passage of a guidewire must first be attempted. Straight guidewires can be made floppy if they have retractable cores, and this allows easy passage frequently. At times, hydrophilic coudé-tipped torque guidewires are helpful. If the orifice can be engaged with the tip of the guidewire but the guidewire cannot be advanced, the tip of the endoscope should be pivoted toward the contralateral orifice while the guidewire is advanced through the endoscope just enough to keep the guidewire engaged in the orifice. The guidewire should then be advanced against the back wall of the bladder, effectively changing the vector force so that the wire can be advanced through a severe J deformity (Figure 11–5). With the guidewire advanced, an exchange catheter can be advanced over the guidewire for injection of contrast material, to be exchanged later for another guidewire or an open-ended catheter. A coudé-tipped guidewire or floppy-tipped guidewire (with a removable core guide) can be advanced through such exchange catheters to facilitate bypassing stones or severe kinks. A push–pull maneuver (pulling the exchange catheter while pushing the guidewire) frequently straightens the ureter as a result of resistance from the exchange catheter, allowing advancement of the guidewire. To increase resistance, an occlusion balloon ureteral catheter can be inflated and with gentle traction can help straighten a kinked or tortuous ureter. Additional helpful maneuvers include deep exhalation, thus elevating the diaphragm, external cephalad pressure by an assistant, or Trendelenburg patient positioning.

Double-J catheters are used to facilitate internal drainage due to obstruction from ureteral angulation and internal or external ureteral compression; they are also used to help decrease the likelihood of sepsis or obstruction in the presence of steinstrasse after extracorporeal shock wave lithotripsy. Double-J stents increase the internal lumen of the ureter. This increase may be used to one's advantage in the setting of a narrow ureter. Placing a double-J catheter and postponing the ureteroscopy for a few days significantly decreases the difficulty of the subsequent procedure. Double-J stents disrupt normal ureteral peristalsis. These stents can be placed over a guidewire or with a closed leading end. With proper placement of the proximal end into the renal pelvis, the J should project in the lateral position when seen on fluoroscopy or x-ray. Projecting in an anterior–posterior position suggests a proximal ureteral location. Proximal-J stent placement can be confirmed by renal ultrasonography during placement in pregnant patients. If it is too long, the distal end in the bladder can result in severe irritative voiding symptoms; if too short, it is more likely to migrate proximally beyond the ureteral orifice into the ureter. In the latter situations, drainage cannot be ensured, and the stent must be extracted with a ureteroscope or snared with a ureteral stone basket.

Patients must be informed that internalized stents have been placed. Frequently, they will not feel the stent. When the stent is left in place for prolonged periods, the likelihood of incrustations, poor drainage, and difficult extraction is increased. It is unclear whether double-J stents facilitate drainage because of drainage around the catheter or via the numerous side holes communicating with the internal lumen. New helically ridged double-J ureteral stents likely enhance ureteral stone passage through unidirectional ratchet-like motion over the external ridges during respiratory and body wall motion. Other complications include distal migration into the bladder, distal migration beyond the bladder neck (resulting in total urinary incontinence), and flank pain during micturition secondary to reflux. The catheter can be removed with forceps via a flexible or rigid cystoscope or by pulling a string that has been attached to the distal end of the catheter and left exiting through the meatus. Although double-J catheters have potential complications, they can help ensure internal urinary drainage.

Balloon dilators can be used to ease passage of ureteroscopes (rigid or flexible; see Chapter 8) and extract intact large calculi. Balloons are routinely passed over a guidewire. Woven balloons have a tight, unfolded outer surface that shortens in longitudinal length when inflated. In contrast, nonwoven varieties are folded and may be difficult to pass after initial inflation and deflation; however, they do not shorten in length with inflation. Balloons inflated alongside distal ureteral calculi can result in balloon perforation or extrusion of the calculus outside the ureteral lumen. Balloon inflation is best achieved with ratcheted or torqued syringe aids directed with pressure gauges. Ureteral access sheaths, frequently made with a hydrophilic coating, can be placed over a guidewire. They dilate the ureter without the need for a ureteral balloon and simplify multiple passages up the ureter.

Retrograde endopyelotomy is an alternative to laparoscopic and open surgical repair, and percutaneous antegrade approaches. After documentation of the exact location of the ureteropelvic junction obstruction under fluoroscopic control, a 150-cm superstiff Lunderquist guidewire is advanced into the renal pelvis. The endoscope is removed and the retrograde endopyelotomy device (Acucise) is advanced over the guidewire under fluoroscopic control. After the incising wire is directed laterally, the balloon is inflated during cautery. Successful results are seen in approximately 80% of patients. An internal endopyelotomy double-J stent, 14F at the proximal end, straddling the ureteropelvic junction, and tapered to 6–8F as it enters and coils in the bladder, or a routine 7F double-J ureteral stent is placed over the stiff guidewire and left in place for 6 weeks. Placing a standard double-J catheter before this procedure dilates the ureter and eases passage of the Acucise and the endopyelotomy double-J catheter.

A large selection of endoscopic baskets is available to entrap and remove material including calculi, sloughed papillae, bulky tumors, fungal bezoars, and foreign bodies. Baskets are designed with and without filiform leaders and can be advanced on their own or, more commonly, through the working ports of flexible and rigid ureteroscopes. Round wire baskets can be torqued to help entrap the target material. A few (2–3) wired baskets are used for large material, while numerous (4–6) wired baskets are used for small or numerous objects. Flat-wired baskets can engage stones effectively. If twisted, however, the wire can fold and transform into a knifelike edge. Once the basket is engaged, one should ensure that the endothelium is not entrapped. Gentle traction helps extract these foreign materials. Engaged baskets may be difficult to disengage. Occasionally, one must cut the handle and place a ureteroscope alongside the basket to facilitate stone and basket extraction. Nitinol baskets have rounded tops and decrease potential endothelial trauma.

Transurethral injections can be performed through a variety of endoscopes. Newer injectables include fibrin glue, Botox, and bulking agents for deflux procedures.

Resectoscopes are endoscopes with sheaths of 10–30F (Figure 11–6) designed for transurethral surgery; they allow urologists to excise, fulgurate, or vaporize tissue from the lower genitourinary tract. Applying an alternating current at high frequencies decreases muscular contractions and allows for cutting and coagulation properties. A pure sine wave is optimal for cutting, whereas dampened oscillating waveforms are best for coagulation. It is possible to combine the two waves to allow for simultaneous cutting and coagulation. A ground plate, as an indifferent electrode, usually applied over the hip, is required. The cutting current results in rapid vaporization of tissue, allowing the cutting loop to move easily through tissue with minimal resistance, and separates the chip, enabling easy flow into the bladder. Rapid succession of cutting sweeps allows rapid surgical excision. In contrast, a coagulation current results in less rapid vaporization and thus decreased separation of tissue from the cutting current. If a traditional resectoscope does not cut tissue, the operator should check for a broken resecting loop, a broken or disconnected cable or generator, or a conductive irrigant (as with saline) that diffuses the current. In contrast, plasmakinetic or bipolar resectoscopes send current from one edge of the endoscopic loop to the other. A high electrical current is generated locally at the loop and effectively vaporizes tissue on contact. Due to the bipolar design, conductive irrigants are used with these bipolar resectoscopes. Resection can also be performed with lasers in a similar fashion.

Before transurethral surgery, the urethra should be calibrated with sounds to ensure ease in placing the resectoscope. Urethral sounds and probes come in numerous varieties (Figure 11–7). An Otis urethrotome can be used to incise the urethra at the 12-o'clock position, thereby decreasing the potential for stricture disease in narrow urethras. Generous use of a water-soluble lubricant is indicated. Before placement of the resectoscope, the loop should be inspected for defects and for appropriate engagement to ensure complete retraction into the sheath, thereby allowing resected tissue to flow easily into the bladder. The endoscope can be placed under direct vision, especially if the patient has not recently been cystoscoped. Alternatively, a Timberlake obturator allows for blind placement of the resectoscope sheath. Older endoscopes require the operator to intermittently remove the working element to allow evacuation of bladder contents. Contemporary endoscopes have an additional channel for continuous operation. An alternative is a percutaneous suprapubic drainage catheter, which allows for maximal continuous flow. Orientation with identification of landmarks, such as the verumontanum and the ureteral orifices, before resection dramatically decreases the potential for complications. Bladder lesions are best resected with minimal bladder distention to decrease the likelihood of perforation. A Bugbee electrode can be used for point coagulation of bleeding points or pathologic lesions. A rollerball can be used to coagulate large areas. Transurethral resection can be used to resect an obstructing prostate gland, to drain prostatic abscesses, or to unroof the ejaculatory duct in select infertility patients.

TURP is a time-tested procedure for resecting prostatic tissue and decreasing symptoms of urinary obstruction. In experienced hands, this can be done with minimal complications. New, alternative procedures are being investigated, especially with patients who are poor anesthetic risks, whose life expectancy is limited, or who are averse to TURP. Those with small glands or with bladder neck contractures have been treated by transurethral incision of the prostate from a point just distal to the ureteral orifices to the verumontanum. Transcystoscopic urethroplasty, also known as prostatic balloon dilatation, dilates the prostatic urethra under visual and fluoroscopic control. Intraurethral coils can be placed in high-risk patients to avoid permanent catheter drainage. Thermotherapy treatment delivers temperatures of 41°C to 44°C for 60 minutes. Obstructing median lobes are unsuited for such techniques. Interstitial laser ablation of the prostate gland is another method for the management of prostatic enlargement. A variety of bipolar systems are available that allow for vaporization of prostatic tissue. Hemorrhage is limited compared to formal resection techniques, and takes longer to remove an equivalent amount of tissue. Long-term studies are required to compare a variety of newer techniques with TURP.

There are various cutting techniques for resecting an obstructing prostate gland during TURP. All require good vision, a comfortable operator, identification of the surgical capsule, and established goals that are met before starting additional stages of the procedure. Pulsatile arterial bleeders should be coagulated first and venous hemorrhage next. Occasionally, arterial bleeders cannot be coagulated without additional resection of tissue. An Ellik bulb or piston syringe should be available to evacuate resected tissue. At the conclusion of the procedure, one should ensure adequate resection and hemostasis, and perform an inspection for forgotten chips of tissue and possible injuries. A Foley catheter should be placed into the bladder and irrigated to confirm unobstructed flow and adequate hemostasis. If an undermined trigone is suspected, a coudé-tipped catheter, a finger in the rectum, or a stylet inserted into the catheter can help in proper placement. The Foley balloon should be inflated 20 mL + 1 mL for each gram of resected tissue. Gentle traction on the catheter can aid hemostasis.

Video cameras are routinely attached to the optical eyepiece while transurethral surgery is performed. Use of the camera helps to reduce the risk of cervical disc disease and distance the surgeon from blood products. It is an excellent resource to improve the teaching of endoscopic surgery.

Acute complications include intra- or extraperitoneal rupture of the bladder, rectal perforation, incontinence, incision of a ureteral orifice with possible reflux or stricture, hemorrhage, gas explosion (especially during resection of a bladder lesion at the dome in the presence of accumulated gas), epididymitis, sepsis, and transurethral resection syndrome. The transurethral resection syndrome is characterized by delusional hyponatremia resulting in possible confusion, congestive heart failure, or pulmonary edema. It is secondary to a large amount of fluid being absorbed, usually through a perforation of a low-pressure system such as the venous sinusoids. If perforations are noted, especially into a sinus, the height of the irrigating solution should be lowered, hemostasis achieved, and the procedure brought to a rapid conclusion. Other complications include impotence (with excessive coagulation) and urethral stricture disease. After an adequate TURP, retrograde ejaculation almost always occurs.

Most bladder calculi originating from the upper tract pass spontaneously through the urethra. In contrast, bladder calculi resulting from outlet obstruction may require endoscopic extraction. Many of these calculi can be washed out or extracted with the aid of various forceps or a resectoscope loop. Calculi too large to pass through an endoscopic sheath first require fragmentation. Visual lithotrites with crushing jaws or a punch-type mechanism are effective. Introduction of these bulky devices is potentially dangerous. A distended bladder facilitates effective engagements of the stone without injuring the bladder wall. Twisting the lithotrite before crushing ensures that the bladder wall is free from the instrument.

Other methods available to fragment bladder calculi include ultrasonic, electrohydraulic, laser, and pneumatic lithotrites. Ultrasonic lithotrites use vibratory energy delivered via a rigid metal transducer. An offset endoscopic lens is required. Gentle pressure of the transducer against the stone facilitates fragmentation; excessive pressure can erode or perforate the bladder wall. A hollow core with suction extracts the fragments. Electrohydraulic lithotripsy generates a spark gap, resulting in a shock wave. It is delivered at the end of a flexible catheter and can be applied as single or repetitive shocks. Fragmentation can be performed with normal saline. A rheostat can adjust the power output. A high setting can result in the stone caroming to various locations in the bladder; lower settings result in suboptimal fragmentation. To optimize fragmentation, the tip of the lithotrite should be a few millimeters away from the stone. To protect the endoscopic optics, the endoscope should be kept at a distance. Shock waves fragment brittle material, such as the stone or a lens. Biologic tissues are elastic and are unharmed as long as the spark gap does not touch them. Air-driven, jack-hammer-like devices (rigid and flexible) can be used for stone fragmentation. Pneumatic lithotrites are effective with minimal tissue trauma. They use reusable probes and are powered by compressed gas. The photothermal mechanism of holmium lasers is effective in fragmenting all types of stones, large, small and multiple bladder stones and is now the most popular lithotrite. Uric acid calculi produce small amounts of cyanide gas when fragmented with holmium lasers; no clinical sequelae have been documented.

Lasers

Lasers (light amplification by stimulated emission of radiation) have been used through flexible and rigid endoscopes. Carbon dioxide and argon lasers result in tissue penetration that is inadequate for the needs of urology. Neodymium:YAG lasers give adequate tissue coagulation and are useful for various lesions. The holmium:YAG system is excellent for stone fragmentation and tissue ablation and is now the most popular system in use. Disadvantages are the lack of adequate tissue for histopathologic evaluation and the initial cost of machinery.

Ultrasonography

Ultrasound has found increased application to the lower genitourinary tract. It results in minimal discomfort; gives a three-dimensional appreciation of the shape, size, and volume of organs and disease; and can provide direct intervention. Various transducers are available; high-megahertz transducers are required for superficial structures (for example, scrotal structures) to assess testicular disease (including tumors and torsion), while low-megahertz transducers are reserved for deep structures (for example, guiding percutaneous access for kidneys and bladders). Intervening tissue can significantly reduce image quality.

Transrectal ultrasound is valuable in evaluating the prostate to determine size and confirm digital information or survey the prostate based on an elevated prostate specific antigen to help determine the presence and stage of a suspected malignant tumor. Because of the low incidence of detecting malignancies (1.6–7%), mass screening programs are not cost effective. Direct needle biopsies, with automatic biopsy mechanisms, are quick, well tolerated, and result in reliable tissue cores and less pain than traditional needles (such as Tru-Cut) directed under digital palpation. Percutaneous drainage tubes, radioactive seed implants, and temperature coils used for cryosurgery of the prostate can be placed safely under transrectal ultrasonic guidance. Transrectal ultrasonography can yield unreliable images that often are misinterpreted by the novice. Pitfalls include faulty instrument settings, poor coupling caused by feces or gas, and unrecognized artifacts resulting from reverberation, deflection, shadowing, or enhancement.

Suprapubic ultrasonography can help to assess prostate anatomy, especially size and intravesical extension. It can help to evaluate the bladder for residual urine and for calculi that are questionable on plain abdominal radiographs. (Changing the patient's position can shift the position of a calculus.) Distal ureteral stones can be identified, especially when visualized through a full bladder used as an acoustic window. Double-J stents, incrustations, diverticula, and large malignant lesions can be identified. The procedure also can direct placement of suprapubic cystostomy drainage catheters.

Additional applications include endocavitary, color, Doppler, and dynamic ultrasonography. Endocavitary ultrasound, which includes transvaginal, transurethral (Figure 11–8), and transcystoscopic techniques, can delineate vaginal, urethral, and bladder disease. Endoureteral ultrasound can help in the identification of crossing vessels, preferably before an endopyelotomy. Color and Doppler ultrasound can assess blood flow as related to erectile dysfunction. Dynamic ultrasound can supplement urodynamic findings. Ultrasound applied to the lower genitourinary tract causes minimal discomfort and provides valuable information.