Chapter 31. Appendix, Meckel's, and Other Small Bowel Diverticula

The first descriptions of the appendix date to the 16th century.1–3 Although sketched in the anatomic notebooks of Leonardo da Vinci around 1500, the appendix was not formally described until 1524 by da Capri4 and 1543 by Vesalius.5 Perhaps the first description of a case of appendicitis was by Fernel in 1554,6 in which a 7-year-old girl with diarrhea was treated with a large quince. Soon thereafter, she developed severe abdominal pain and died. Autopsy showed that the quince had obstructed the appendiceal lumen, resulting in appendiceal necrosis and perforation. For the next few centuries, such cases of appendicitis were typically diagnosed at autopsy.

Amyand is credited with the first appendectomy in 1736, when he operated on a boy with an enterocutaneous fistula within an inguinal hernia.7 On exploration of the hernia sac, he discovered the appendix, which had been perforated by a pin resulting in a fecal fistula. As a result of his original description, an inguinal hernia containing the appendix carries Amyand's eponym to this day.8 Nearly 150 years passed until Lawson Tait in London presented the first successful transabdominal appendectomy for gangrenous appendix in 1880.9 Less than a decade later, in 1886, Reginald Fitz of Harvard Medical School first described the natural history of the inflamed appendix, coining the term “appendicitis.”10 In 1889, Charles McBurney of the Columbia College of Physicians and Surgeons in New York presented his series of cases of surgically treated appendicitis and in so doing described the anatomic landmark that now bears his name. McBurney's point is the location of maximal tenderness “very exactly between an inch and a half and two inches from the anterior spinous process of the ileum on a straight line drawn from that process to the umbilicus.”11 In the 1890s, Sir Frederick Treves of London Hospital advocated conservative management of acute appendicitis followed by appendectomy after the infection had subsided12; unfortunately, his youngest daughter developed perforated appendicitis and died from such treatment.

Numerous advances in the diagnosis and treatment of appendicitis have emerged in the past 125 years. Nonetheless, acute appendicitis continues to challenge surgeons to this day.

Embryologically, the appendix and cecum develop as outpouchings of the caudal limb of the midgut loop in the 6th week of human development. By the 5th month, the appendix elongates into its vermiform shape. At birth, the appendix is located at the tip of the cecum, but, because of unequal elongation of the lateral wall of the cecum, the adult appendix typically originates from the posteromedial wall of the cecum, caudal to the ileocecal valve. The appendix averages 9 cm in length,3 with its outside diameter ranging from 3 to 8 mm and its lumen ranging from 1 to 3 mm. The base of the appendix is consistently found by following the teniae coli of the colon to their confluence at the base of the cecum. The appendiceal tip, however, can vary significantly in location (Fig. 31-1). Although usually located in the right lower quadrant (RLQ) or pelvis, the tip can occasionally reside in the left lower or right upper quadrants (RUQ).

The arterial supply of the appendix comes from the appendicular branch of the ileocolic artery, which originates posterior to the terminal ileum and enters the mesoappendix near the base of the appendix (Fig. 31-2). Lymphatic drainage flows to lymph nodes along the ileocolic artery.

Epidemiology

Addiss and associates13 estimated the incidence of acute appendicitis in the United States to be 11 cases per 10,000 population annually. The disease is slightly more common in males, with a male: female ratio of 1.4:1. In a lifetime, 8.6% of males and 6.7% of females can be expected to develop acute appendicitis. Young age is a risk factor, as nearly 70% of patients with acute appendicitis are younger than 30 years. The highest incidence of appendicitis in males is in the 10- to 14-year-old age group (27.6 cases per 10,000 population), while the highest female incidence is in the 15- to 19-year-old age group (20.5 cases per 10,000 population). Patients at extremes of age are more likely to develop perforated appendicitis. Overall, perforation was present in 19.2% of cases of acute appendicitis. This number was significantly higher, however, in patients younger than 5 and older than 65 years. Although less common in people older than 65 years, acute appendicitis in the elderly progresses to perforation more than 50% of the time.13

Etiology and Pathophysiology

Appendicitis, diverticular disease, and colorectal carcinoma have been shown to be diseases of developed civilizations. Burkitt14 found an increased incidence of appendicitis in Western countries compared to Africa, as well as in wealthy, urban communities compared to rural areas. He attributed this to the Western diet, which is low in dietary fiber and high in refined sugars and fat, and postulated that low-fiber diets lead to less bulky bowel contents, prolonged intestinal transit time, and increased intraluminal pressure. Burkitt theorized that the combination of firm stool leading to appendiceal obstruction and increased intraluminal pressure causing bacterial translocation across the bowel wall resulted in appendicitis. In examining appendixes removed for reasons other than appendicitis, he found fecaliths to be more prevalent in Canadian (32%) than in South African (4%) adults. In a group of patients with appendicitis, fecaliths were more common in Canadians (52%) than in South Africans (23%).15 He felt this was confirmation that appendiceal obstruction resulted in appendicitis. Of note, however, the majority of patients with appendicitis in his study did not have evidence of a fecalith.

Wangensteen extensively studied the structure and function of the appendix and the role of obstruction in appendicitis.16,17 Based on anatomic studies, he postulated that mucosal folds and a sphincter-like orientation of muscle fibers at the appendiceal orifice make the appendix susceptible to obstruction. He proposed the following sequence of events to explain appendicitis: (1) Closed-loop obstruction is caused by a fecalith and swelling of the mucosal and submucosal lymphoid tissue at the base of the appendix; (2) intraluminal pressure rises as the appendiceal mucosa secretes fluid against the fixed obstruction; (3) increased pressure in the appendiceal wall exceeds capillary pressure and causes mucosal ischemia; and (4) luminal bacterial overgrowth and translocation of bacteria across the appendiceal wall result in inflammation, edema, and ultimately necrosis. If the appendix is not removed, perforation can ensue.

Although appendiceal obstruction is widely accepted as the primary cause of appendicitis, evidence suggests that this may be only one of many possible etiologies. First, some patients with a fecalith have a histologically normal appendix, and the majority of patients with appendicitis show no evidence for a fecalith.15,18,19 Arnbjornsson and Bengmark20 studied at laparotomy the appendixes of patients with suspected appendicitis. They found the intraluminal pressure of the appendix prior to removal to be elevated in only 8 of 27 patients with nonperforated appendicitis. They found no signs of obstruction in the remaining patients with nonperforated appendicitis, as well as all patients with a normal appendix. Taken together, these studies imply that obstruction is but one of the possible etiologies of acute appendicitis.

Presentation

Perhaps the most common surgically correctable cause of abdominal pain, the diagnosis of acute appendicitis remains difficult in many instances. Some of the signs and symptoms can be subtle to both the clinician and the patient and may not be present in all instances. Arriving at the correct diagnosis is essential, however, as a delay in diagnosis may allow progression to perforation and significantly increased morbidity and mortality. Incorrectly diagnosing a patient with appendicitis, although not catastrophic, often subjects the patient to an unnecessary operation.

The classic presentation of acute appendicitis begins with crampy, intermittent abdominal pain, thought to be due to obstruction of the appendiceal lumen. The pain may be either periumbilical or diffuse and difficult to localize. This is typically followed shortly thereafter with nausea; vomiting may or may not be present. If nausea and vomiting precede the pain, patients are likely to have another cause for their abdominal pain, such as gastroenteritis. Classically, the pain migrates to the right lower quadrant as transmural inflammation of the appendix leads to inflammation of the peritoneal lining of the right lower abdomen. This usually occurs within 12–24 hours of the onset of symptoms. The character of the pain also changes from dull and colicky to sharp and constant. Movement or Valsalva maneuver often worsens this pain, so that the patient typically desires to lie still; some patients describe pain with every bump in the car or ambulance ride to the hospital. Patients may report low-grade fever up to 101°F (38.3°C). Higher temperatures and shaking chills should again alert the surgeon to other diagnoses, including appendiceal perforation or nonappendiceal sources. When questioned, patients who have appendicitis commonly report anorexia; appendicitis is unlikely in those with a normal appetite.

The surgeon is constantly reminded that in practice, the classic presentation of acute appendicitis is not present in all patients. Patients may have none or only a few of the symptoms just described. For instance, they may not notice or recall the initial colicky pain. When the pain becomes constant, it may localize to other quadrants of the abdomen due to an alteration in appendiceal anatomy as in late pregnancy or malrotation. In patients with a retrocecal appendix, the pain may never localize until generalized peritonitis from perforated appendicitis occurs. Urinary or bowel frequency may be present due to appendiceal inflammation irritating the adjacent bladder or rectum. Because appendicitis is so common, a high index of suspicion for appendicitis is warranted in all patients with abdominal pain.

Perforated Appendicitis

It is a commonly held belief that if left untreated, appendiceal inflammation will progress inevitably to necrosis, and ultimately to perforation. The time course of this progression varies among patients. In one study of the natural history of appendicitis, the authors questioned patients undergoing appendectomy for suspected appendicitis about their duration of symptoms.21 Patients with nonperforated appendicitis reported an average of 22 hours of symptoms prior to presentation to the hospital, while patients with perforated appendicitis reported an average of 57 hours. However, 20% of cases of perforated appendicitis presented within 24 hours of the onset of symptoms; one of those patients had symptoms for only 11 hours. Although concern for perforation should be present when evaluating a patient with more than 24 hours of symptoms, the clinician must remember that perforation can develop more rapidly.

Some authors have questioned whether some perforations in acute appendicitis are attributable to delay in diagnosis after a patient seeks medical attention. Velanovich and Satava postulated a surgeon's misdiagnosis rate (the percentage of normal appendixes found at appendectomy) to be inversely related to the perforation rate (the percentage of perforated appendixes found at laparotomy).22 They believed that surgeons are obliged to operate quickly when appendicitis is suspected, thus minimizing the likelihood of perforation in exchange for a higher rate of misdiagnosis. More recent studies suggest that this reasoning is flawed. Temple and colleagues showed that patients with perforated appendicitis were operated on more quickly than those with nonperforated appendicitis (6.5 vs 9 hours), but perforated patients had significantly longer prehospital symptoms (57 vs 22 hours).21 These findings are confirmed by two other studies, both showing that longer duration of prehospital delay is the major contributor to perforation.23,24 Perforation after presenting to surgical attention appears to be uncommon.

When acute appendicitis has progressed to appendiceal perforation, other symptoms may be present. Patients will often complain of two or more days of abdominal pain, but their duration of symptoms may be shorter, as previously discussed. The pain usually localizes to the right lower quadrant if the perforation has been walled off by surrounding intra-abdominal structures including the omentum, but it may be diffuse if generalized peritonitis ensues. The pain may be so severe that patients do not remember the antecedent colicky pain. Patients with perforation often have rigors and high fevers to 102°F (38.9°C) or above. A history of poor oral intake and dehydration may also be present.

Most patients with perforated appendicitis present with symptoms related to the inflamed appendix itself or to a localized intraperitoneal abscess from perforation. Other more rare presentations do occur, however. These are most likely to occur in the very young and very old, who cannot express their symptoms and often present late in the course of their disease. For instance, abscesses can also form in the retroperitoneum due to perforation of a retrocecal appendix, or in the liver from hematogenous spread of infection through the portal venous system. An intraperitoneal abscess could fistulize to the skin, resulting in an enterocutaneous fistula. Pylephlebitis (septic portal vein thrombosis) presents with high fevers and jaundice and can be confused with cholangitis; it is a dreaded complication of acute appendicitis and carries a high mortality.25 On occasion, patients will have bilious vomiting and obstipation due to a small bowel obstruction resulting from appendiceal perforation. Because appendicitis is so common, these rare presentations should alert the surgeon to the possibility of appendicitis.

Diagnosis

History and Physical Examination

As always, the diagnosis begins with a thorough history and physical examination. The patient should be asked about the classic symptoms of appendicitis, but the surgeon should not be dissuaded by the absence of many of the symptoms. Many patients with acute appendicitis do not have a classic history. Because the differential diagnosis of appendicitis is extensive, patients should be queried about certain symptoms that may suggest an alternative diagnosis. Surgeons must also remember that a previous appendectomy does not definitively exclude the diagnosis of appendicitis, as “stump appendicitis” (appendicitis in the remaining appendiceal stump after appendectomy), although rare, has been described.26

On inspection, patients look mildly ill and may have slightly elevated temperature and pulse. They often lie still to avoid the peritoneal irritation caused by movement. The surgeon should systematically examine the entire abdomen, starting in the left upper quadrant away from the patient's described pain. Maximal tenderness is typically in the right lower quadrant, at or near McBurney's point, located one-third of the way from the anterior superior iliac spine to the umbilicus. This tenderness is often associated with localized muscle rigidity and signs of peritoneal inflammation, including rebound, shake, or tap tenderness. RLQ tenderness is most consistent of all signs of acute appendicitis27,28; its presence should always raise the specter of appendicitis, even in the absence of other signs and symptoms. Because of the various anatomic locations of the appendix, however, it is possible for the tenderness to be in the right flank or right upper quadrant, the suprapubic region, or the left lower quadrant. Patients with a retrocecal or pelvic appendix may have no abdominal tenderness whatsoever. In such cases, rectal examination can be helpful to elicit right-sided pelvic tenderness.

Multiple signs can be detected on physical examination to contribute to the diagnosis of appendicitis. Rovsing's sign, pain in the right lower quadrant on palpation of the left lower quadrant, results from localized peritoneal inflammation in the right lower quadrant. Psoas sign, pain with flexion of the leg at the right hip, can be seen with a retrocecal appendix due to inflammation adjacent to the psoas muscle. The obturator sign, pain with rotating the flexed right thigh internally, indicates inflammation adjacent to the obturator muscle in the pelvis.

In cases of perforated appendicitis, patients can look gravely ill, appearing flushed with dry mucous membranes and considerable elevations in temperature or pulse. If sepsis has developed, blood pressure can be depressed. If the perforation has been walled off by surrounding structures to create an abscess or phlegmon, a mass may be palpable in the right lower quadrant. If free intraperitoneal rupture has occurred, the patient can have signs of generalized peritonitis with diffuse rebound tenderness.

Laboratory Studies

Laboratory studies can be helpful in the diagnosis of appendicitis, but no single test is definitive. A white blood cell count (WBC) is perhaps the most useful laboratory test. Typically, the WBC is slightly elevated in nonperforated appendicitis but may be quite elevated in the presence of perforation. The clinician must remember, however, that the WBC can be normal in patients with acute appendicitis, particularly in early cases. Serial WBC measurements improve the diagnostic accuracy, with a rising value over time commonly seen in patients with appendicitis.29 Urinalysis is performed to diagnose other potential causes for abdominal pain, specifically urinary tract infection and ureteral stone. Significant hematuria with colicky abdominal pain suggests ureterolithiasis, and testing directed at this diagnosis is indicated. A urinary tract infection, on the other hand, is not uncommon in patients with appendicitis. Its presence does not exclude the diagnosis of acute appendicitis, but it should be identified and treated. Although pyuria suggests urinary tract infection, it is not uncommon for the urinalysis in a patient with appendicitis to show a few white blood cells solely due to inflammation of the ureter by the adjacent appendix.

In certain patient populations, other laboratory tests are indicated. Measurement of serum liver enzymes and amylase can be helpful in diagnosing liver, gallbladder, or pancreatic disease in patients complaining of midabdominal or RUQ pain. In women of childbearing age, the urine β-human chorionic gonadotropin should be checked to alert the clinician to the possibility of ectopic or concurrent pregnancy. Ectopic pregnancy is another cause of RLQ pain that demands emergent diagnosis and treatment. Concurrent pregnancy should be known before a patient with suspected appendicitis is subjected to ionizing radiation from imaging studies or to general anesthesia.

Diagnostic Scores

Diagnostic scoring systems have been developed in an attempt to improve the diagnostic accuracy of acute appendicitis.18,30 The most prominent of those scores, developed by Alvarado,30 was based on a retrospective analysis of 305 patients with abdominal pain suspicious for appendicitis. This scoring system gives points for symptoms (migration of pain, anorexia, and nausea), physical signs (RLQ tenderness, rebound tenderness, and pyrexia), and laboratory values (leukocytosis and a left shift). Although these scores can help guide clinical thinking, they do not markedly improve diagnostic accuracy.31 With the recent improvement in imaging studies, these scores play a smaller role in diagnosis.

Imaging Studies

The potential imaging modalities for diagnosis of acute appendicitis include plain radiographs, ultrasound (US), and computed tomography (CT). Prior to the widespread use of modern imaging techniques, plain abdominal films were often obtained in patients with abdominal pain, and a right lower quadrant fecalith (or appendicolith) was considered pathognomonic for acute appendicitis. A number of studies question this teaching, however. Teicher and colleagues18 reviewed the abdominal radiographs of 200 appendectomy patients—100 with pathologically proven appendicitis and 100 with a normal appendix. Of those with appendicitis, 10.5% had an appendicolith on x-ray, compared to 3.3% of those without appendicitis. An extensive review of appendectomy specimens at the Mayo Clinic19 showed that fecaliths or appendiceal calculi were present in 9% of patients with nonperforated appendicitis and 21% of those with perforated appendicitis. Interestingly, fecaliths were also present in 7% of patients with suspected appendicitis who had a pathologically normal appendix and in 2% of patients who had an appendectomy for other reasons.

These studies show that fecaliths are not pathognomonic for appendicitis, as some patients with abdominal pain and a fecalith have a normal appendix. In addition, fecaliths are not common enough in patients with appendicitis to be used as a reliable sign. As a result, plain abdominal radiographs are neither helpful nor cost-effective and are not recommended for the diagnosis of acute appendicitis. Plain radiographs are indicated in elderly patients with severe abdominal pain, in whom a perforated viscus is included in the differential diagnosis. In this patient population, an upright chest x-ray can assess for the presence of free air.

Abdominal ultrasonography is a popular imaging modality for acute appendicitis. Findings that suggest appendicitis include thickening of the appendiceal wall, loss of wall compressibility, increased echogenicity of the surrounding fat signifying inflammation, and loculated pericecal fluid (Fig. 31-3). The advantages of ultrasound include its widespread availability, as well as the avoidance of ionizing radiation and the side effects of intravenous contrast such as renal toxicity and allergic reactions. In addition, ultrasound (both abdominal and transvaginal) is particularly useful in assessing obstetric and gynecological causes of abdominal pain in women of childbearing age. Ultrasound is highly operator-dependent, however, and it is frequently unable to visualize the normal appendix.32 A recent meta-analysis of 14 prospective studies showed ultrasound to have a sensitivity of 0.86 and a specificity of 0.81.33

CT is yet another imaging modality for acute appendicitis. CT benefits from a high diagnostic accuracy for appendicitis33 and visualization and diagnosis of many of the other causes of abdominal pain that can be confused with appendicitis. The radiographic findings of appendicitis on CT include a dilated (>6 mm), thick-walled appendix that does not fill with enteric contrast or air, as well as surrounding fat stranding to suggest inflammation (Fig. 31-4).34 In a meta-analysis of 12 prospective studies, CT demonstrated a sensitivity of 0.94 and a specificity of 0.95.33 CT thus has a high negative predictive value, making it particularly useful in excluding appendicitis in patients for whom the diagnosis is in doubt. Appendicitis is highly unlikely if enteric contrast fills the lumen of the appendix and no surrounding inflammation is present. The clinician must remember, however, that a CT performed early in the course of appendicitis might not show the typical radiographic findings. In confusing cases, it is reasonable to repeat the CT after 24 hours of observation.

A number of recent prospective studies have compared the accuracy of CT and ultrasound in imaging the appendix (Table 31-1).32,35,36 Balthazar and associates35 performed CT and ultrasound on 100 consecutive patients with suspected appendicitis. The sensitivity of CT was considerably higher (96% for CT, 76% for US), while the specificity was comparable (89% for CT, 91% for US), yielding a higher accuracy for CT (94 vs 83%). CT was also able to provide an alternative diagnosis in more patients and was better able to visualize abscesses or phlegmons (Fig. 31-5). Horton and colleagues36 randomized patients with suspected appendicitis to either CT or ultrasound. Their findings echo those of Balthazar, with both CT and ultrasound having high specificity (100% for CT, 90% for US) but CT having significantly higher sensitivity (97 vs 76%). Yet another prospective study showed similar results, with CT having higher sensitivity (96 vs 62%) and specificity (92 vs 71%) than ultrasound.32 Again, CT was also better able to visualize other intra-abdominal pathology in the absence of appendicitis.

In a study of 100 patients evaluated by CT with rectal and intravenous contrast, Rao and coworkers37 showed that CT can reduce the use of hospital resources and costs. CT changed the management of 59 patients, avoiding 13 unnecessary appendectomies and eliminating a total of 50 inpatient hospital days for observation of unexplained abdominal pain. Even factoring in the cost of the CT scans, the authors calculated a net savings of US$447 per patient.

Taken together, these studies suggest an algorithm for evaluation of patients with suspected acute appendicitis. Patients with a history, physical examination, and laboratory studies classic for appendicitis should undergo appendectomy. In those with an evaluation suggestive but not convincing for appendicitis, further imaging is warranted. In women of childbearing age, this should begin with a pelvic ultrasound to evaluate for ovarian pathology. In other patients, transabdominal ultrasound or abdominopelvic CT should be considered, depending on study availability and expertise of the consulting radiologist. CT does have the advantage of improved accuracy in diagnosing both appendiceal and other intra-abdominal pathology. This can be supplemented with rectal contrast CT, if needed, to better visualize the appendix.32,37 Patients with a CT showing nonperforated appendicitis should undergo appendectomy. In many instances, patients with a normal CT do not require hospital admission. If symptoms persist, admission to the hospital for observation, and perhaps a repeat CT scan, is warranted.

Differential Diagnosis

Because many of its signs and symptoms are nonspecific, the differential diagnosis of acute appendicitis is extensive and includes virtually all possible abdominal sources of pain, as well as some nonabdominal sources (Table 31-2). However, some diagnoses are more likely than others in certain patient groups. For instance, in young males with a suggestive history and physical examination, acute appendicitis is the most likely cause of RLQ pain. Meckel's diverticulitis causes similar symptoms but is relatively uncommon.38 Gastroenteritis is considerably more common and should be expected when nausea and vomiting precede the abdominal pain, or when diarrhea is a prominent symptom. Crohn's disease affecting the terminal ileum may resemble appendicitis in its initial presentation, but on further questioning the patient typically describes a subacute course, including fever, weight loss, and pain.

In middle-aged and older adults, other inflammatory conditions should be considered, including peptic or duodenal ulcer (with fluid tracking into the right paracolic gutter), cholecystitis, and pancreatitis. In addition, cecal or sigmoid diverticulitis can be confused with acute appendicitis. Cecal diverticulitis is quite similar in pathogenesis and presentation to appendicitis, because cecal diverticula, like the appendix, are true diverticula containing all layers of the intestinal wall. Because a redundant, floppy sigmoid colon can extend to the right side of the abdomen, patients with sigmoid diverticulitis can sometimes present with RLQ pain. Those patients typically describe a quicker progression to localized tenderness, as well as a prodrome of an alteration in bowel habits. Malignancies can present with acute RLQ pain due to perforation of a cecal carcinoma or appendicitis caused by a mass obstructing the appendiceal orifice.39 These patients will also typically have guaiac-positive stools, anemia, and a history of weight loss.

In women of childbearing years, the diagnosis of RLQ pain can be even more difficult. In addition to the causes of RLQ pain mentioned for young men, young women can also have pain from obstetric and gynecological causes such as ruptured ovarian cyst or follicle, ovarian torsion, ectopic pregnancy, acute salpingitis, and tubo-ovarian abscess. A complete history including recent menstrual history, as well as pelvic examination, can be helpful in differentiating these causes of pain from acute appendicitis. Nonetheless, appendicitis can be difficult to diagnose in this patient population, and higher rates of misdiagnosis have been described in women of childbearing age.40

Special Considerations

Children.

Appendicitis most commonly affects children age 10–19, with an overall incidence of approximately 20 cases per 10,000 population annually.13 Among those younger than 20, infants aged 0–4 have the lowest incidence of appendicitis (2 cases per 10,000 annually), but up to two-thirds will present with perforation.41 Perforation is common because infants often present later in their disease course and because of the difficulty in obtaining an accurate history. The diagnosis is further complicated by diseases of childhood that can mimic appendicitis. For instance, mesenteric adenitis, an inflammation of the mesenteric lymph nodes secondary to upper respiratory tract infection, can present with fever and RLQ pain. Streptococcal pharyngitis and bacterial meningitis can also present with fever, nausea, and abdominal pain. These diagnoses and others including ovarian cysts, ovarian torsion, urinary tract infection, pelvic inflammatory disease, and complications of a Meckel's diverticulum should be considered when evaluating children or adolescents for suspected appendicitis.

In children with an equivocal history and physical examination, imaging with either a CT scan or US can significantly reduce the negative appendectomy rate from 14 to 37% down to 2 to 10%.42 The pertinent question is which study is preferable. As with adults, both CT and US have been shown to be highly accurate in diagnosing appendicitis in children, although CT scan is believed to have a higher specificity and sensitivity. In an early study Garcia Pena and associates compared ultrasonography and rectal contrast CT in 139 children with suspected appendicitis and found CT to be more sensitive (97% for CT, 44% for US), more specific (94% for CT, 93% for US), and more accurate (94% for CT, 76% for US).43 CT correctly changed the management of 73% of patients, while ultrasound correctly changed 19%. More recent meta-analysis and reviews evaluating CT and/or ultrasound in pediatric populations found the specificity of the two imaging modalities to be similar (92–95%) but the sensitivity of ultrasound (88–90%) to be less than that of CT scan (94–95%).42,44 An important determinant in the diagnostic success of ultrasound is the body mass index (BMI) of the child. The sensitivity of ultrasound has been reported by some to be 76% in children with a BMI below 25, 37% in children with a BMI greater than 25, and 82% in one study in which the patient population had a mean BMI of 17.42,45,46

The use of CT can be recommended for children with one caveat. The radiation from a CT in childhood theoretically causes a small increase in the lifetime risk of certain cancers.47 Based on estimated radiation exposure from a CT scan, studies have hypothesized that a 1-year-old and 15-year-old would have a 0.18 and 0.11% lifetime risk, respectively, of fatal radiation-induced malignancy following a CT scan.42 Therefore, clinicians should consider the risks and benefits of CT, and efforts should be directed toward reducing radiation dose when imaging children.48 In the pediatric patients with suspected appendicitis, an algorithm starting with an ultrasound, especially in low BMI children and females, followed by CT scan if the ultrasound is equivocal may allow the maximum benefit of radiologic imaging while minimizing potential deleterious radiation effects. The use of magnetic resonance imaging (MRI) in the evaluation of children has only recently begun to be investigated. Although its ability to identify the appendix has been established, the use of MRI in the diagnosis of appendicitis in children requires further study.

Elderly.

Although appendicitis is more common in younger age groups, it is still an important cause of abdominal pain in the elderly. Perhaps because of a diminished inflammatory response, the elderly can present with less impressive symptoms and physical signs, longer duration of symptoms, and decreased leukocytosis compared to younger patients.49 Perforation is thus more common, occurring in as many as 50% of patients older than 65.13 These patients may have cardiac, pulmonary, and renal conditions, resulting in considerable morbidity and mortality from perforation. In one series, the mortality from perforated appendicitis in patients older than 80 was 21%.50 These factors argue that RLQ pain in elderly patients must be aggressively investigated. Because of the multiple other possible causes of abdominal pain in this patient population (including malignancy, diverticulitis, and perforated peptic ulcer disease), prompt CT scan is advocated when the diagnosis is in question.

Pregnancy.

The diagnosis of acute appendicitis in the pregnant patient can be particularly challenging, as nausea, anorexia, and abdominal pain may be symptoms of both appendicitis and normal pregnancy. In addition, the gravid uterus can displace the abdominal viscera, shifting the location of the appendix from the right lower quadrant. Appendicitis affects 1 in every 1400 pregnancies, an incidence similar to that of the nonpregnant female population.51 It can occur in any trimester, with perhaps a slight increase in frequency during the second trimester.51,52 Perforation is more common in the third trimester, however, and results from a longer duration from the onset of symptoms to operation.53 The differential diagnosis of appendicitis includes not only the conditions possible in nonpregnant women but also certain conditions specific to pregnancy: ectopic pregnancy, chorioamnionitis, preterm labor, placental abruption, and round ligament pain.

In the first and early second trimesters, the presentation of appendicitis is similar to that seen in nonpregnant women. In the third trimester, women may not present with RLQ pain due to displacement of the appendix by the gravid uterus. Baer and associates performed barium enemas on normal pregnant women and found the appendix to migrate superiorly toward the right upper quadrant in later stages of pregnancy.54 Their findings suggest that appendicitis should present with RUQ or flank pain in late pregnancy. Two retrospective studies contradict this, however, showing that even in the third trimester, pain and tenderness are more common in the right lower than the right upper quadrant.51,52 Nonetheless, RUQ pain did predominate in some third-trimester patients with appendicitis in each study,51,52 reminding the clinician that right upper quadrant and right flank symptoms could be due to appendicitis in an appendix displaced by the gravid uterus. Recent studies highlight the difficulty of assigning a clinical picture to a pregnant patient with appendicitis. Brown et al55 reviewed case-control studies attempting to correlate preoperative signs and symptoms with the postoperative diagnosis of appendicitis in pregnant patients. Although patients presented with RUQ pain, RLQ pain, and fevers, only nausea, vomiting, and peritonitis were found to significantly correlate with the diagnosis of appendicitis.

Ultrasound is accurate in pregnancy56 and is a useful first radiological study because it has no known adverse fetal effects.57 Rectal contrast CT has also been shown to be highly accurate in the pregnant population.58 Although ionizing radiation has risks to the fetus, the radiation from a typical abdominopelvic CT is below the threshold of 5 rad at which teratogenic effects are seen.59 When the diagnosis is in doubt, the risk of radiation should be weighed against the risk of spontaneous abortion from an unnecessary laparotomy or from undiagnosed appendicitis progressing to perforation. Hospital admission with close observation for progression of symptoms is a viable alternative if the risks of radiation from CT scan are deemed excessive. Additionally, MRI has been recently used to aid in the diagnosis of appendicitis in the pregnant patient when ultrasound results are equivocal. In those pregnant patients with a normal or inconclusive ultrasound, MRI is a diagnostic option, with accuracy that rivals CT; MRI has a sensitivity of 80% and specificity of 99%, compared with 85.7 and 97.4% for CT. Although MRI does not carry a risk of radiation, it does have theoretical risks of static and time-varying magnetic fields, heating effects of the radiofrequency pulses and acoustic noise generated by the spatial encoding gradients do exist. To date, however, no adverse effects of MRI on the developing fetus have been reported.60

The pregnant patient should proceed directly to appendectomy if appendicitis is suspected. A normal appendix is not an uncommon finding, as negative appendectomy has been reported in approximately one-third of cases due to the difficulty of diagnosis in this population.51,52,61 Negative appendectomy should not be considered an error in diagnosis, because the risk to the fetus varies directly with the severity of appendicitis. In one series, fetal loss occurred in only 1 (3%) of 30 negative laparotomies.51 Fetal mortality rises to 5% in cases of nonperforated appendicitis and increases to 20–35% when the appendix perforates.55,61 These data warrant an aggressive approach to appendectomy. Early negative exploration is justified to minimize the likelihood of progression to perforation.

As laparoscopic appendectomy has become increasingly popular, it has been utilized more frequently during pregnancy.62 Pregnancy can increase the complexity of the procedure, as the gravid uterus can make laparoscopic visualization difficult, particularly if the appendix is located in the pelvis. In addition, carbon dioxide insufflation of the abdomen results in fetal hypercarbia and decreased placental blood flow, the effects of which have not been completely studied.63 Recent case series, however, have supported the safety of laparoscopic appendectomy in the pregnant patient. In a retrospective review of 45 cases, Lemieux et al64 demonstrated that 4% of patients had a major complication (uterine perforation, intra-abdominal abscess), 4% of patients had a minor complication (cystitis, ileus), 18% delivered before 37 weeks gestation, and there was no fetal loss. There was also no difference in complications, preterm delivery, or operative time associated with performing the appendectomy during the first, second, or third trimester. A retrospective review directly comparing laparoscopic to open appendectomy in 42 pregnant women found no intra- or postoperative complications in either group and one fetal loss in both groups.65 Thus, the feasibility and safety of laparoscopy during pregnancy are supported by these studies, but larger studies are required for it to become fully accepted.

Immunocompromise.

The immunocompromised state alters the normal response to acute infection and wound healing. Appendicitis affects all types of patients and must be considered in those who have undergone organ transplant, are receiving chemotherapy, have hematological malignancy, or are infected with the human immunodeficiency virus (HIV). The differential diagnosis of abdominal pain in this population is broad and includes hepatitis, pancreatitis (from medications or cytomegalovirus infection), acalculous cholecystitis, intra-abdominal opportunistic infections (cytomegalovirus colitis or mycobacterial ileitis), secondary malignancies (lymphoma or Kaposi's sarcoma), graft-versus-host disease, and typhlitis. This broad differential diagnosis often results in delay in diagnosis and late presentation to surgical evaluation, at which time perforation may be more likely.66,67

Appendicitis in patients with HIV and acquired immunodeficiency syndrome (AIDS) presents unique challenges. Abdominal pain is not an uncommon symptom in these patients, making differentiation between surgical and nonsurgical causes difficult. Nonetheless, immunocompromised patients with appendicitis present with symptoms similar to those of the general population,66 and RLQ pain, nausea, and anorexia. Fever and WBC may not be helpful in this population, so imaging studies, particularly CT, have been supported by some authors.67 There is no specific contraindication to operation in immunocompromised patients, so once diagnosed with appendicitis, appendectomy should be performed promptly.

Nonoperative Management

Appendectomy was one of the first intra-abdominal operations performed, and appendicitis has long been a surgically treated disease. Rare descriptions of nonsurgical management dot the surgical literature, however. Treves was an advocate of early nonoperative management of acute appendicitis, even prior to the advent of antibiotics.12 In the postantibiotic era, Coldrey presented his retrospective series of 471 patients with appendicitis treated with antibiotics.68 This treatment failed in at least 57 patients, with 48 requiring appendectomy and 9 requiring drainage of an appendiceal abscess. An early randomized controlled trial, performed by Eriksson and associates, sought to address this issue.69 Their results show a high rate of recurrence of appendicitis treated nonsurgically. The authors randomized 40 adults with presumed appendicitis to appendectomy or 10 days of intravenous and oral antibiotics. Eight (40%) of the 20 patients in the antibiotic group required appendectomy within 1 year: one patient for perforation within 12 hours of randomization and another seven for recurrent appendicitis (one of whom had perforation). Based on the high rate of failure with antibiotics alone, nonoperative management of acute appendicitis has not been recommended.

Recently, a larger randomized clinical trial evaluating antibiotic therapy versus appendectomy as the primary treatment for acute appendicitis in unselected patients was performed.70 In this study 202 patients were assigned to antibiotic treatment and 167 patients to appendectomy. Treatment efficacy, defined as definite improvement without the need for surgery within a median follow-up of 1 year for the antibiotic group and confirmed appendicitis or another appropriate surgical indication at the time of the operation for the appendectomy group, was found to be similar between the antibiotic and appendectomy groups (90.8 and 89.2% respectively). In the antibiotic group, recurrent appendicitis occurred in 13.9% after a median of 1 year. A third of the recurrences occurred within 10 days and two-thirds occurred within 3 and 16 months after discharge. Minor complications were similar between the two groups while major complications, defined as the need for reoperation, abscess, bowel obstruction, wound rupture or hernia, and serious anesthesia or cardiac-related problems, were three times higher in the appendectomy group. Close evaluation of this study, however, highlights the need for further studies and caution when applying their findings to clinical practice. Specifically, only 52.5% of those allocated to the antibiotic group completed antibiotic treatment. The remaining patients were transferred to the appendectomy group based on either the patient's or surgeon's discretion. Evaluation of those patients transferred to the surgery group indicate that they had a higher WBC and elevated temperature suggesting that they may have been clinically sicker. The efficacy of the antibiotic group reported as 90.8% was based only on those that completed antibiotic therapy and thus excluded the potentially sicker patients who crossed over from the antibiotic group to the surgery group. Evaluation of efficacy based on intention-to-treat (all 202 patients originally allocated to the antibiotic group including the 47.5% that switched to surgery) results in an efficacy of 48% for the antibiotic group. These studies suggest that antibiotic treatment may be a useful first-line treatment for acute appendicitis in selected patients; however, further studies are required to determine their usefulness as the lone treatment option. Nevertheless, antibiotic treatment may be a useful temporizing measure in environments with no surgical capabilities such as in space flight and submarine travel.71

Preoperative Preparation

When the decision is made to perform an appendectomy for acute appendicitis, the patient should proceed to the operating room with little delay to minimize the chance of progression to perforation. Such occurrences are rare, however, as most cases of appendiceal perforation occur prior to surgical evaluation.23,24 Patients with appendicitis may be dehydrated from fever and poor oral intake, so intravenous fluids should be begun, and pulse, blood pressure, and urine output should be closely monitored. Markedly dehydrated patients may require a Foley catheter to ensure adequate urine output. Severe electrolyte abnormalities are uncommon with nonperforated appendicitis, as vomiting and fever have typically been present for 24 hours or less but may be significant in cases of perforation. Any electrolyte deficiencies should be corrected prior to the induction of general anesthesia.

Intravenous antibiotics have been shown to reduce significantly the incidence of postoperative wound infection and intra-abdominal abscess.72 Antibiotics should be administered 30 minutes prior to incision to achieve adequate tissue levels. The typical flora of the appendix resembles that of the colon and includes gram-negative aerobes (primarily Escherichia coli) and anaerobes (Bacteroides spp.). No standardized antibiotic regimen exists. Acceptable options include a second-generation cephalosporin or a combination of antibiotics directed at gram negatives and anaerobes. In nonperforated appendicitis, a single preoperative dose of cefoxitin suffices.73 In cases of perforation, an extended course of at least 5 days of antibiotics is advocated.74

Open versus Laparoscopic Appendectomy

Once the diagnosis of appendicitis is made, the surgeon must decide whether to perform an open (OA) or laparoscopic (LA) appendectomy. Numerous randomized controlled trials have compared these two methods, sometimes with conflicting results.75,76 Meta-analyses and systematic reviews have combined these studies to address the controversy (Table 31-3).77–79 These meta-analyses have similar findings, which can be summarized as follows: (1) OA can be performed more quickly; (2) LA patients have less postoperative pain and reduced narcotic requirements; (3) there is a trend toward reduced length of stay with LA; (4) LA patients have fewer wound infections; (5) OA patients develop fewer intra-abdominal abscesses; (6) LA patients return to work more quickly; (7) operating room and hospital costs are less with OA; and (8) societal costs may be less with LA.77–79 Based on the data available, one cannot convincingly recommend either OA or LA over the other. Each method has its advantages and disadvantages that should be considered when deciding how to perform appendectomy.

One situation in which laparoscopic appendectomy may be advisable is when the diagnosis of appendicitis is in doubt. This can be particularly useful in women of childbearing age, in whom obstetric and gynecological pathology may also be likely. In this population, a normal appendix can be found in more than 40% of patients with suspected appendicitis.80 Laparoscopy can thus be both diagnostic and therapeutic, and a laparotomy can be avoided if gynecologic pathology is found. The ovaries, fallopian tubes, and uterus can be examined for nonappendiceal causes of abdominal pain, including ovarian cyst or torsion, endometriosis, or pelvic inflammatory disease. Laparoscopy makes this evaluation considerably easier and less morbid for the patient. In one study, when a normal appendix was discovered, gynecological pathology was found in 73% of women explored laparoscopically but only 17% of women who had an open appendectomy.81 Although diagnostic accuracy will likely improve in young women with more widespread use of CT scans, this population will continue to provide diagnostic dilemmas that may be aided by laparoscopy.

Open Appendectomy.

If open appendectomy is chosen, the surgeon must then decide on the location and type of incision. Prior to incision, a single dose of antibiotics should be administered, typically a second-generation cephalosporin.73 The patient should be reexamined after the induction of general anesthesia, which enables deep palpation of the abdomen. If a mass representing the inflamed appendix can be palpated, the incision can be centered at that location. If no appendiceal mass is detected, the incision should be centered over McBurney's point, one-third of the distance from the anterior superior iliac spine to the umbilicus. A curvilinear incision, now known as McBurney's incision, is made in a natural skin fold. It is important not to make the incision too medial or too lateral. An incision placed too medial opens onto the anterior rectus sheath, rather than the desired oblique muscles, while an incision placed too lateral may be lateral to the abdominal cavity.

The operation proceeds much as McBurney first described it in 1894.82 The incision extends through the subcutaneous tissue, exposing the aponeurosis of the external oblique muscle, which is divided, either sharply or with electrocautery, in the direction of its fibers (Fig. 31-6). A muscle-splitting technique is typically used, in which the external oblique, internal oblique, and transversus abdominis muscles are separated along the orientation of their muscle fibers. The peritoneum is thus exposed, grasped with forceps, and opened sharply along the orientation of the incision, taking care not to injure the underlying abdominal contents. Hemostats can be placed on the peritoneum to facilitate its identification at the time of wound closure. Cloudy fluid may be encountered on entering the peritoneum. Although some advocate bacterial culture of the peritoneal fluid, studies show that this neither helps direct the antibiotic regimen83 nor reduces infectious complications.84

With a correctly placed incision, the cecum will be visible at the base of the wound. The incision should be explored with a finger in an attempt to locate the appendix. If the appendix is palpable and free from surrounding structures, it can be delivered into the incision. Frequently, the appendix is palpable, but it adheres to surrounding structures. Filmy adhesions can be divided using blunt dissection, but thicker adhesions should be divided under direct vision. To facilitate this, the cecum can be partially delivered into the incision to provide better exposure of the appendix. If necessary to improve exposure, the incision can be extended medially by partially dividing the rectus muscle or laterally by further dividing the oblique and transversus abdominis muscles. If the appendix cannot be visualized, it can be located by following the teniae coli of the cecum to the cecal base, from which the appendix invariably originates. Once located, the appendix is delivered through the incision. Grasping the mesentery with a Babcock clamp can sometimes facilitate this maneuver. Care should be taken to avoid perforation of the appendix, with spillage of pus or enteric contents into the abdomen.

The arterial supply to the appendix, which runs in the mesoappendix, is now divided between clamps and tied with 3-0 polyglactin or silk suture. This is usually performed in an antegrade fashion, from the appendiceal tip toward the base. Division of the artery to the appendiceal base is necessary to ensure that the entire appendix can be removed without leaving an excessively long appendiceal stump.

In excising the appendix, the surgeon must decide whether or not to invert the appendiceal stump. Traditionally, the appendix was ligated and divided, and its stump was inverted with a purse-string suture for the theoretical purpose of avoiding bacterial contamination of the peritoneum and subsequent adhesion formation.85,86 However, recent prospective studies show no advantages to appendiceal stump inversion.87,88 In one such study, 735 appendectomy patients were randomly assigned to ligation plus inversion or simple ligation of the appendiceal stump. There was no difference between the two groups in the incidence of wound infection or adhesion formation, and operating time was shorter in the simple ligation group. Inversion may also have the deleterious effect of deforming the cecal wall, which could be misinterpreted as a cecal mass on future contrast radiographs.88 Furthermore, the long-standing notion that stump inversion reduces postoperative adhesions was discredited by Street and colleagues.89 In their analysis, postoperative adhesions requiring operation were significantly increased in the inversion group.

To divide the appendix, the surgeon can use either suture ligation or a gastrointestinal stapler. For ligation, two hemostat clamps are placed at the base of the appendix. The clamp closest to the cecum is removed, having crushed the appendix at that site. Two heavy, absorbable sutures such as 0 chromic gut is used to doubly ligate the appendix, and the appendix is subsequently divided proximal to the second clamp. The exposed mucosa of the appendiceal stump can be cauterized to minimize the theoretical risk of postoperative mucocele, although no data exist to support this. If appendiceal stump inversion is chosen, a seromuscular purse-string 3-0 silk suture is placed in the cecum around the appendiceal base after ligation but prior to division of the appendix. The purse-string suture should be placed approximately 1 cm from the base of the appendix, as placing it too close to the appendix makes stump inversion difficult. After the appendix is divided, the purse-string suture is tightened and tied while the assistant uses forceps to invaginate the appendiceal stump. Alternatively, the appendix can be divided at its base using a TA-30 stapler. Again, the stump need not be inverted, but can be if desired, using interrupted Lembert sutures with 3-0 silk suture. No matter how the appendix is divided, the residual appendiceal stump should be no longer than 3 mm to minimize the possibility of stump appendicitis in the future.26

Occasionally, inflammation at the tip of the appendix makes antegrade removal of the appendix difficult. In such cases, the appendix can be removed in a retrograde fashion. In so doing, the appendix is divided at its base using one of the methods described previously. The mesoappendix is then divided between clamps, starting at the appendiceal base and progressing toward the tip (Fig. 31-7).

In certain cases, the appendiceal inflammation extends to the base of the appendix or beyond to the cecum. Division of the appendix through inflamed, infected tissue leaves the potential for leakage of cecal contents with a resultant abscess or fistula. Ensuring that the resection margin is grossly free of active inflammation can minimize this risk. If the base of the cecum is also inflamed but there is sufficient uninflamed cecum between the appendix and the ileocecal valve, an appendectomy with partial cecectomy can be performed using a stapling device.90 Care should be taken to avoid narrowing the cecum at the ileocecal valve. If the inflammation extends to the ileocecal junction, an ileocecectomy with primary anastomosis may be necessary.

After the appendix is removed, hemostasis is achieved and the right lower quadrant and pelvis are irrigated with warm saline. The peritoneum is closed with a continuous 0 absorbable suture; this layer provides no strength but helps to contain the abdominal contents during abdominal wall closure. The internal and external oblique muscles are then closed in succession using continuous 0 absorbable suture. To decrease postoperative narcotic requirements, the external oblique fascia can be infused with local anesthetic. Interrupted absorbable sutures are typically placed in Scarpa's fascia, and the skin can be closed with a subcuticular absorbable suture. With a preoperative dose of intravenous antibiotics and primary closure of the skin, fewer than 5% of patients with nonperforated appendicitis can be expected to develop a wound infection.91

Laparoscopic Appendectomy.

Multiple port placements for laparoscopic appendectomy exist. The authors utilize a three-port technique, with one umbilical and one suprapubic port. Although the third port can be placed in either the left or right lower quadrant, we prefer the left lower quadrant. This follows the laparoscopic principle of triangulation, such that the port locations direct the camera and instruments toward the right lower quadrant for optimal visualization of the appendix.

The patient is positioned supine on the operating room table with the left arm tucked (Fig. 31-8). The video monitor is placed at the patient's right side, because once pneumoperitoneum is performed, the surgeon and assistant both stand on the patient's left. A single dose of a second-generation cephalosporin is administered prophylactically. Prior to incision, a nasogastric tube and a Foley catheter are placed to decompress the stomach and urinary bladder. A Foley catheter can be avoided if a reliable patient urinates immediately prior to entering the operating room. A 1- to 2-cm vertical or transverse incision is made just inferior to the umbilicus and carried down to the midline fascia. A 12-mm trocar is placed using either Hassan or Veress technique, depending on surgeon preference. After insufflation of the abdomen and inspection through the umbilical port, a 5-mm suprapubic port is placed in the midline, taking care to avoid injury to the bladder, and another 5-mm port is placed in the left lower quadrant. These port sites typically provide excellent cosmesis postoperatively due to their small size and peripheral location on the abdomen.

A 5-mm, 30-degree laparoscope is inserted through the left lower quadrant trocar. Placing the laparoscope in the left lower quadrant allows triangulation of the appendix in the right lower quadrant by instruments placed through the two midline trocars. The surgeon operates the two dissecting instruments and the assistant operates the laparoscope. The appendix is identified at the base of the cecum, and any adhesions to surrounding structures can be lysed with a combination of blunt and sharp dissection supplemented with electrocautery. If a retrocecal appendix is encountered, division of the lateral peritoneal attachments of the cecum to the abdominal wall often improves visualization. Care must be taken to avoid underlying retroperitoneal structures, specifically the right ureter and iliac vessels. The appendix or mesoappendix can be gently grasped with a Babcock clamp placed through the suprapubic port and retracted anteriorly. A dissecting forceps placed through the umbilical port creates a window in the mesoappendix at the appendiceal base. Caution should be taken not to injure the appendiceal artery during this maneuver. As in the open procedure, the base of the appendix should be adequately dissected so that it can be divided without leaving a significant stump.26 The appendix should be divided at the confluence of the appendix and cecum, or just onto the cecal wall, to avoid the possibility of stump appendicitis or mucocele (see Fig. 31-8).

The appendix can be removed in a retrograde fashion, first dividing the appendix, followed by division of the mesoappendix. A laparoscopic gastrointestinal anastomosis (GIA) stapler is placed through the umbilical port and fired across the appendiceal base. After reloading, the stapler is again inserted through the umbilical port and placed across the mesoappendix, which is divided with firing of the stapler. Alternatively, the appendix can be secured using an Endoloop92 (Ethicon, Endo-Surgery, Cincinnati, Ohio) and the mesoappendix with an Endoloop of cautery device. If desired, the appendix can be removed antegrade, by first dividing the mesoappendix prior to directing attention to the base. The appendix should be placed in a retrieval bag and removed through the umbilical port site to minimize the risk of wound infection. The operative field is inspected for hemostasis and can be irrigated with saline. Finally, the fascial defect at the umbilicus is closed with interrupted 0 absorbable suture, and all skin incisions are closed with fine subcuticular absorbable suture.

Postoperative Care

Patients with nonperforated appendicitis typically require a 24- to 48-hour hospital stay. Postoperative care for both the laparoscopic and open approaches is similar. Patients can be started on a clear liquid diet immediately, and their diet can be advanced as tolerated. No postoperative doses of antibiotics are required. Patients can be discharged when they tolerate a regular diet and oral analgesics.

Perforated Appendicitis

When appendicitis progresses to perforation, management depends on the nature of the perforation. If the perforation is contained, a solid or semisolid periappendiceal mass of inflammatory tissue can form, referred to as a phlegmon. In other cases, contained perforation may result in a pus-filled abscess cavity. Finally, free perforation can occur, causing intraperitoneal dissemination of pus and fecal material. In the case of free perforation, the patient is typically quite ill and perhaps septic. Urgent laparotomy is necessary for appendectomy and irrigation and drainage of the peritoneal cavity. If the diagnosis of perforated appendicitis is known, the appendectomy can be performed through an RLQ incision, and the technique follows that previously described for open appendectomy. Sometimes patients with free perforation present with an acute abdomen and generalized peritonitis, and the decision to perform a laparotomy is made without a definitive diagnosis. In such instances, a midline incision is prudent. Once perforated appendicitis is discovered, appendectomy again proceeds as described previously. Peritoneal drains are not necessary, as they do not reduce the incidence of wound infection or abscess after appendectomy for perforated appendicitis.93,94 The final operative decision is whether or not to close the incision. Because of wound infection rates ranging from 30 to 50% with primary closure of grossly contaminated wounds, many advocate delayed primary or secondary closure.91,95 However, a cost-utility analysis of contaminated appendectomy wounds showed primary closure to be the most cost-effective method of wound management.96 Our technique of skin closure is interrupted permanent sutures or staples every 2 cm with loose wound packing in between. Removal of the packing in 48 hours often leaves an excellent cosmetic result with an acceptable incidence of wound infection. Patients are often continued on broad-spectrum antibiotics for 5–7 days and should remain in the hospital until afebrile and tolerating a regular diet.

If the patient does not have signs of generalized peritonitis but an abscess or phlegmon is suspected by history and physical exam, a CT scan can be particularly helpful to confirm the diagnosis. A solid, inflammatory mass in the RLQ without evidence of a fluid-filled abscess cavity suggests a phlegmon. In such instances, appendectomy can be difficult due to dense adhesions and inflammation. Ileocecectomy may be necessary if the inflammation extends to the wall of the cecum. Complications such as inadvertent enterotomy, postoperative abscess, or enterocutaneous fistula may ensue. Because of these potential complications, many support an initially nonoperative approach.97–99 Such an approach is only advisable if the patient is not ill appearing. Nonoperative management includes intravenous antibiotics and fluids as well as bowel rest. Patients should be closely monitored in the hospital during this time. Treatment failure, as evidenced by bowel obstruction, sepsis, or persistent pain, fever, or leukocytosis, requires immediate appendectomy. If fever, tenderness, and leukocytosis improve, diet can be slowly advanced, usually within 3–5 days. Patients are discharged home when clinical parameters have normalized. Using this approach, more than 80% of patients can be spared an appendectomy at the time of initial presentation.97,98

If imaging studies demonstrate an abscess cavity, CT- or ultrasound-guided drainage can often be performed percutaneously or transrectally.100,101 Studies suggest that this approach to appendiceal abscesses results in fewer complications and shorter overall length of stay.99,102 Again, following drainage the patient is closely monitored in the hospital and is placed on bowel rest with intravenous antibiotics and fluids. Advancement of diet and hospital discharge progress as clinically indicated.

Interval Appendectomy

Treatment following initial nonoperative management of an appendiceal phlegmon or abscess is controversial. Some recommend interval appendectomy102–105 (appendectomy performed approximately 6 weeks after inflammation has subsided), while others consider subsequent appendectomy unnecessary.98,106,107 Factors to be considered when advising patients on interval appendectomy include a relatively low incidence of future appendicitis (8–10% and often associated with an appendicolith) and a morbidity associated with an interval appendectomy of approximately 11%.106 These factors must be weighed against the higher morbidity associated with an immediate appendectomy in the setting of acute recurrent appendicitis in the future (as high as 36% when appendicitis is associated with a phlegmon or abscess)106 as well as the possibility of an ongoing appendiceal pathology, including inflammatory bowel disease and cancer.103,105,106 Because it can now be performed laparoscopically on an outpatient basis with low morbidity,104,108 interval appendectomy should be considered for patients who were initially treated with nonoperative management, but there is not convincing evidence to recommend this approach.

Normal Appendix

Because of the difficulty in diagnosing appendicitis, it is not uncommon for a normal appendix to be found at appendectomy. Sometimes referred to as misdiagnosis, this can occur more than 15% of the time, with considerably higher percentages in infants, the elderly, and young women.40 Negative appendectomy is to be avoided when possible, because of the risk of surgical complications and the cost associated with unnecessary surgery.109 Nonetheless, in certain instances, the diagnosis is in doubt, and a noninflamed appendix is found at laparotomy or laparoscopy. The surgeon must then decide whether or not to remove the appendix. For multiple reasons, it is advisable to remove the grossly normal appendix. First, if the pain recurs and the appendix has been removed, appendicitis will no longer be a possibility and can be removed from the differential diagnosis. If the patient suffers RLQ pain in the future and the appendix has not been removed, but the patient has a classic RLQ scar, a surgeon evaluating the patient may assume a history of appendectomy and erroneously remove appendicitis from consideration. As laparoscopic appendectomy becomes more popular, this may even be true for patients with port site scars suggestive of appendectomy. Finally, there is strong evidence that a surgeon's gross assessment of the appendix can be inaccurate. In one study, 11 (26%) out of 43 appendectomy specimens described as normal by the surgeon showed acute appendicitis on pathological examination.110 As a result, removal of a grossly normal appendix at the time of appendectomy is recommended.

When a normal appendix is discovered at appendectomy, it is important to search for other possible causes of the patient's symptoms. The terminal ileum can be inspected for evidence of terminal ileitis, which could be from infectious causes (Yersinia or tuberculosis) or Crohn's disease. In the absence of perforation, resection should not be performed for Crohn's disease and appropriate medical therapy should be initiated postoperatively. The ileum should also be evaluated for an inflamed or perforated Meckel's diverticulum, which should be excised. In females, the ovaries, fallopian tubes, and uterus should be examined for pathology as well. Evaluation of the left adnexa can be difficult through an RLQ incision, highlighting the utility of laparoscopy in female patients.

Although rare, chronic appendicitis can explain persistent abdominal pain in some patients. Patients do not present with the typical symptoms of acute appendicitis. Instead, they complain of weeks to years of RLQ pain and may have had multiple medical evaluations in the past. When queried, they may describe an initial episode with more classic symptoms of acute appendicitis, for which no treatment was delivered.111 Diagnosis can be difficult, as laboratory and radiological studies are typically normal. Pathology evaluation revealing chronic inflammation confirms the diagnosis. Because the diagnosis is often uncertain preoperatively, laparoscopy can be a useful tool to allow exploration of the abdomen.112

As CT scans become more widely utilized, it is likely that an increasing number of asymptomatic appendicoliths will be discovered. As discussed previously, appendicoliths are not pathognomonic for appendicitis but should only be considered in conjunction with the clinical presentation and other diagnostic studies. Lowe and associates113 studied CT scans of children with suspected appendicitis and compared them to CT scans of children with abdominal trauma. Six (14%) of 44 patients with suspected appendicitis had an appendicolith but proved not to have appendicitis. In addition, 2 (3%) of the 74 trauma patients had an appendicolith on CT. These children were not followed to see if appendicitis developed later in life, but the considerable number of asymptomatic appendicoliths seen on adult abdominal radiographs suggests that many patients with an appendicolith will never develop appendicitis.18,19 Based on this, appendectomy for asymptomatic appendicolith cannot be recommended.

Neoplasms of the appendix are rare, affecting less than 1% of appendectomies. Signs and symptoms of appendicitis prompt appendectomy in up to 50% of patients, and it is not uncommon for the patients with an appendiceal neoplasm to have acute appendicitis as well.114 Patients may also present with a palpable mass, intussusception, urologic symptoms, or an incidentally discovered mass on abdominal imaging or at laparotomy for another purpose. Typically, the diagnosis is not known until laparotomy or pathologic evaluation of the appendectomy specimen, but preoperative diagnosis may become more common as imaging techniques become more widely used. Because of their common embryologic origin, the appendix and colon are susceptible to many of the same neoplastic growths. The most common appendiceal tumors include cystic neoplasms, carcinoid tumors, adenocarcinoma, and metastases. Other tumors have been reported but are extremely rare, such as lymphoma, stromal tumors (leiomyoma and leiomyosarcoma), and Kaposi's sarcoma.115

Cystic Neoplasms and Pseudomyxoma Peritonei

Sometimes referred to as mucoceles, mucinous neoplasms of the appendix include a spectrum of diseases, including simple cyst, mucinous cystadenoma, mucinous cystadenocarcinoma, and pseudomyxoma peritonei. Mucocele is not a true pathologic diagnosis and instead refers to the macroscopic appearance of an appendix distended with mucus. Any of the above conditions can form a mucocele, but the more specific diagnostic term is preferable.116 A simple cyst results from nonneoplastic occlusion of the appendiceal lumen, is usually less than 2 cm in diameter, and is often an incidental finding at appendectomy. In contrast, mucinous cystadenomas, benign tumors that represent the majority of “mucoceles,” can grow to 8 cm or larger (Fig. 31-9).117 They typically remain asymptomatic due to slow-growing distension of the appendix and instead present incidentally as a mass on physical examination or abdominal imaging (Fig. 31-10). On plain radiograph or CT, wall calcification is characteristic.116

It is recommended that all mucinous appendiceal masses 2 cm or larger be surgically removed.117 For mucinous cystadenoma, appendectomy is sufficient if the lesion does not involve the appendiceal base. Occasionally, the mass will rupture prior to or at the time of removal, but this rupture is typically contained to the right lower quadrant and is considered localized pseudomyxoma peritonei. If the mass is benign, appendectomy and removal of any residual mucin is curative.118 Laparoscopic appendectomy is not currently recommended because of the possibility of malignancy and spillage of mucin-secreting cells throughout the abdomen.119 Because of an association with colon and rectal carcinoma, a screening colonoscopy is recommended postoperatively.117

Mucinous cystadenocarcinoma represents the malignant form of cystic neoplasms of the appendix. In contrast to cystadenoma, patients are usually symptomatic with abdominal pain, weight loss, an abdominal mass, or signs of acute appendicitis. Increasing abdominal girth may also be present and suggests development of pseudomyxoma peritonei from perforation and peritoneal dissemination of mucin-secreting cells. Diffuse pseudomyxoma peritonei is highly predictive of malignancy; in one series, 95% of patients with pseudomyxoma had an associated mucinous cystadenocarcinoma.117 The recommended treatment consists of right hemicolectomy with debulking of any gross spread of disease and removal of all mucin. It is not uncommon, however, for the diagnosis to be unknown until the time of pathologic evaluation of the appendectomy specimen. In such cases, reoperation with right hemicolectomy is recommended, as 5-year survival for mucinous cystadenocarcinoma is 75% after hemicolectomy and less than 50% after appendectomy alone.120 Some referral centers advocate extensive initial resections including omentectomy, as well as repeated debulking procedures for recurrent disease.121

Adenocarcinoma

Primary adenocarcinoma of the appendix is classified into two types: mucinous (discussed previously) and colonic. The colonic type is less common, less likely to secrete mucus, and more likely to present with acute appendicitis due to obstruction of the appendiceal lumen.116 Because of similarities with colon carcinoma, appendiceal adenocarcinomas are classified as Dukes stage A, B, C, and D, with 5-year survival rates of 100, 67, 50, and 6%, respectively. The colonic type has a less favorable prognosis, with only 41% 5-year survival after treatment, compared to 71% for the mucinous type. The optimal treatment is right hemicolectomy, and reoperation should be recommended if the diagnosis is made on pathologic evaluation of an appendectomy specimen.120

Carcinoid Tumors

The most common neoplasm of the appendix, carcinoid tumors comprise more than 50% of all appendiceal tumors.114 Among malignant tumors of the appendix, carcinoids are less aggressive and carry a much more favorable prognosis than adenocarcinomas, with 5-year survival approaching 90%.122 Most appendiceal carcinoids are found incidentally at the time of appendectomy for appendicitis. However, because the majority of appendiceal carcinoids are located at the tip of the appendix, the carcinoid mass is the cause of appendicitis only 25% of the time.115 Tumor size is the primary determinant of malignant potential. About 75% of carcinoids are less than 1 cm in size and 5–10% are over 2 cm. Lymph node invasion and distant metastases are exceedingly rare except in tumors over 2 cm.123 Histologically, carcinoids of the appendix are categorized as goblet cell and classic carcinoid. Mortality is higher for goblet cell but is still lower than that of adenocarcinoma.122

Treatment of appendiceal carcinoids is dictated primarily by tumor size. Simple appendectomy is sufficient for tumors less than 1 cm because of the low likelihood of lymph node involvement. For masses larger than 2 cm, right hemicolectomy is recommended. Because of a concern for increased metastatic potential, some authors also advocate right hemicolectomy in young patients; in carcinoids at the appendiceal base; and when there is evidence of lymphatic invasion, lymph node involvement, spread to the mesoappendix, tumor-positive resection margins, or cellular pleomorphism with a high mitotic index.123–125

Small Bowel Diverticula

Small bowel diverticula can be characterized according to their anatomic location (duodenal, jejunoileal, and distal ileal diverticula) or the type of diverticula (false or true diverticula). False diverticula do not contain all the layers of the bowel wall. They are acquired defects predominantly located in the duodenal and jejunoileal portions of the small bowel. These diverticula involve herniated mucosa and submucosa and typically occur at points of weakness, where blood vessels enter the mesenteric border of the small bowel. In contrast, a distal ileal (Meckel's) diverticulum is a true diverticulum containing all of the layers of the small bowel. It is a congenital anomaly resulting from the failure of the vitelline duct to obliterate and is located along the antimesenteric border of the distal ileum. Although the presence of small bowel diverticula is not uncommon, most are asymptomatic and thus not appreciated. Less than 4% of small bowel diverticula cause symptoms, including inflammation, hemorrhage, obstruction, perforation, and malabsorption.

Duodenal Diverticula

Duodenal diverticula (DD) account for approximately 45% of small bowel diverticula and have a reported incidence on radiologic and autopsy studies of 5–22%.126,127 They are rarely multiple (12%) and are predominantly located in the medial wall of the second portion of the duodenum (88%).128 When the diverticulum is located adjacent to the ampulla of Vater, as is often the case, it is known as a perivaterian or periampullary diverticulum. DD typically occur in patients aged 50–65 years and are often asymptomatic at presentation. Less than 5% of patients with DD present with symptoms, including nausea, vomiting, RUQ abdominal pain, fevers, chills, and bleeding. These presentations result from one of many potential complications, including inflammation, obstruction of the duodenum or biliary-pancreatic duct, fistula formation in the bile duct, bezoar formation inside the diverticulum, and perforation. Although it is the most unusual complication, DD perforation is the most serious and can carry a mortality of up to 20%. Perforation usually results from acute inflammation but may also result from enterolithiasis, ulceration, increased intraluminal pressure (eg, during endoscopy), abdominal trauma, gallstones, or ischemia. Perforation usually occurs posteriorly and can result in a retroperitoneal abscess and sepsis. Anterior perforation can also occur, resulting in intraperitoneal spillage or communication with the pancreas, colon, gallbladder, or aorta causing a duodenocolic fistula or acute gastrointestinal hemorrhage secondary to perforation into the aorta.126,129

The nonspecific nature of the presenting symptoms and their commonality with other gastrointestinal diseases such as pancreatitis, cholecystitis, cholangitis, and peptic ulcer disease highlight the fact that the diagnosis of a complicated DD is often one of exclusion. Radiologic studies including plain abdominal films and ultrasound may be helpful to exclude other etiologies but are not definitive. CT scan and upper endoscopy are the modalities of choice for evaluation. In the case of an inflamed diverticulum, CT may demonstrate a thickened duodenal wall and surrounding fat inflammation. If perforation has occurred, an extraluminal collection of air and fluid (predominantly retroperitoneal) may be identified. Additionally, the administration of oral contrast with a CT scan or an upper gastrointestinal swallow study may define the extent of a leak in the case of a perforation. However, it is not uncommon to be unable to identify a DD on CT scan, and additional studies may be required. Side-viewing endoscopy and endoscopic retrograde cholangiopancreatography (ERCP) are very valuable in correctly diagnosing the presence of a DD as well as potentially treating some of the associated complications. Successful endoscopic management of hemorrhage, duodenal obstruction, pancreatobiliary obstruction resulting in pancreatitis or cholangitis, and retroperitoneal abscess drainage associated with a DD have been reported.130–133

The management of DD depends on the presence or absence of symptoms and the clinical stability of the patient. Given the precarious location of a DD and the morbidity associated with resection, asymptomatic DD discovered on imaging or endoscopy for other reasons should be observed. Symptomatic DD can be managed endoscopically, nonoperatively, or with surgical exploration and resection or bypass. If inflammation with or without perforation is present, nonoperative management, including nasogastric decompression, antibiotics, serial examinations, and radiologic-guided drainage if an abscess is present, has been reported. This approach can be considered in patients with mild symptoms who are clinically stable or when CT confirms a contained leak.126,128,130,134 If the patient is not a candidate for nonoperative management because of hemodynamic instability, generalized peritonitis, or persistent severe symptoms, the choice of surgical intervention depends on such factors as the location of the diverticulum and other intraoperative findings. A simple closure of the perforated diverticulum or diverticulectomy with single- or double-layer duodenal closure after kocherizing the duodenum is the treatment of choice if there is minimal inflammation and the anatomy of the diverticulum permits. After repair, appropriate drainage tubes should be placed and the greater omentum can be used to reinforce the repair. It is imperative to avoid damaging the pancreatic and distal common bile duct during the repair, so cannulation of the ampulla of Vater either retrograde or antegrade through the cystic duct (with subsequent cholecystectomy) can be performed to help visualize the ampulla prior to dissecting the diverticulum. If there is significant inflammation at the site of the diverticulum or the diverticulum lays buried in the pancreatic head or the papilla lays deep in the diverticulum, a diversion should be performed. Diversion can be performed by either a distal gastrectomy with a Billroth-II reconstruction or a Roux-en-Y gastrojejunostomy. Again, appropriate drainage tubes are typically placed to drain the affected area. In addition to diversion and diverticulectomy, segmental duodenal resection for a perforated DD has also been reported for the rare case of a DD located in segment III or IV of the duodenum. A pancreaticoduodenectomy may also be necessary if the DD lies in close proximity to the common bile and pancreatic ducts and the inflammation is thought to be too severe for safe diversion or drainage.126,129,130 If symptoms are related not to perforation of the DD but to obstruction of the pancreaticobiliary system causing cholangitis or pancreatitis, resection of the duodenum may not be required and treatment may consist of diversion of bile flow with a Roux-en-Y choledochojejunostomy and duodenojejnuostomy.130,135

Jejunoileal Diverticula

Least common of the small bowel diverticula, jejunoileal diverticula (JID) have an incidence of 0.002–5% based on postmortem and enteroclysis studies. Their incidence increases with age and peaks in the sixth and seventh decades of life. JID are acquired pseudodiverticula believed to result from a jejunoileal dyskinesia causing increased intraluminal pressures and herniation of the mucosa and submucosa through the weakest site of the muscularis of the bowel wall (ie, the mesenteric border where paired blood vessels enter the bowel wall). They can be single (33%) or multiple (66%) and located in the jejunum (55–80%), ileum (15–38%), or both (5–7%).136 Interestingly, patients with JID also frequently have other coexisting gastrointestinal diverticula, including those found in the colon (20–70%), duodenum (10–40%), esophagus, and stomach (2%) highlighting a potential common etiology.137–139

The diagnosis of a JID is often challenging because most patients are asymptomatic (up to 70%) or present with vague abdominal complaints. There is, in fact, no gold standard imaging technique used to diagnose a JID. Upper gastrointestinal studies with small bowel follow-through as well as traditional enteroclysis and CT enteroclysis studies are beneficial. CT, tagged red blood cell scan, or angiogram may demonstrate findings consistent with a complication of a JID such as inflammation, perforation, or bleeding. Capsule endoscopy and double-balloon endoscopy are useful in diagnosing small bowel disorders and may be of benefit in identifying JID in a nonacute setting.137,140,141 Ultimately, JID are often identified on exploratory laparotomy or laparoscopy for other indications or for the evaluation of chronic or acute symptoms.137

Asymptomatic, incidentally discovered JID need not be resected. When symptomatic, patients with JID can be divided into those with acute or chronic symptoms. Forty to sixty percent of patients with a known diagnosis of JID present with chronic symptoms. These symptoms are often nonspecific and include nausea, vomiting, postprandial bloating, recurrent abdominal pain, cramping, weight loss, fatigue, and failure to thrive. Because of the vague nature of the presenting symptoms, these patients often go undiagnosed or misdiagnosed for several months (average 22 months) prior to being correctly diagnosed.136,141,142 The pathophysiology of the chronic symptoms is believed to be related to either intestinal dyskinesia or bacterial overgrowth from blind loop syndrome due to stasis in the diverticular lumen. When bacterial overgrowth and a blind loop syndrome are present, the patient may develop malabsorption, steatorrhea, and megaloblastic anemia resulting from vitamin B12 deficiency. Frequently, chronic symptoms from JID can be successfully managed medically. Medical management consists of a low-residue diet, antispasmodics, antacids, analgesics, and vitamin B12 supplementation. Bacterial overgrowth and blind loop syndrome can be initially managed with antibiotics. If medical management fails, patients may require resection of the segment of bowel containing the diverticulum with subsequent primary anastomosis.

Approximately 10–19% of patients with JID present with acute, often emergent, symptoms resulting from a complication of the diverticulum, including gastrointestinal hemorrhage, diverticulitis with or without perforation, obstruction, fistula formation, sepsis, liver abscesses and pneumoperitoneum. The presentation and management of a patient with an acute complication of a JID depends on the complication. Inflammation resulting in diverticulitis occurs in 2.3–6.4% of patients with JID and can present as mild abdominal pain or diffuse peritonitis associated with free perforation.136 If perforation occurs in the setting of full-thickness necrosis, it can be associated with a mortality of up to 40%.136,143 Traumatic and foreign body perforations of JID have also been described. If the perforation is contained within the mesentery, nonoperative management with bowel rest and antibiotics with or without percutaneous drainage can be attempted. Similarly, asymptomatic pneumoperitoneum in the setting of a known JID is not an indication for surgery and can be managed conservatively.136,144,145 Lack of clinical improvement after a period of nonoperative management mandates resection of the affected segment of bowel with a primary anastomosis. Similarly, patients presenting with a more significant findings of fever, elevated WBC, peritonitis, and septic physiology require immediate laparotomy with resection of the affected segment of bowel.136

Of patients with JID, 2–4.6% present with obstruction related to adhesions, intussusception, volvulus, and extrinsic compression from a fluid-filled diverticulum or, rarely, from an enterolith formed in the diverticulum causing obstruction at the diverticulum or at the ileocecal valve. Obstruction believed to be secondary to adhesions can initially be managed conservatively. However, if nonoperative management fails, lysis of adhesions and segmental bowel resection of the JID with a primary anastomosis are required. Similarly, surgical resection is indicated for the management of obstruction resulting from intussusception, volvulus, or extrinsic compression.137 Enterolith ileus associated with a JID is best managed by an initial attempt at manual lysis of the stone without an enterotomy. If not possible, the stone can be removed through an enterotomy made in a nonedematous segment of bowel. If one or multiple diverticula appear inflamed or scarred, segmental resection of the involved bowel with a primary anastomosis is mandated. However, many patients often have multiple diverticula over a long stretch of bowel, and thus, if no evidence of inflammation or scarring is present, no resection is indicated.136 Approximately 3–8% of patients with JID present with bleeding complications. Hemorrhage from a JID can be slow and chronic in nature or acute and massive presenting with hemorrhagic shock. Upper and lower endoscopies are often negative, and the diagnosis is made with angiographic and radioactive red blood cell studies. Although treatment with angiographic embolization has been documented, segmental bowel resection is frequently the required treatment.136,146

Meckel's Diverticula

Meckel's diverticula are the most common congenital malformation of the gastrointestinal tract, occurring in approximately 1% of the population.147–149 A Meckel's diverticulum is a true diverticulum containing all three layers of the intestinal wall and results from the failure of the obliteration of the omphalomesenteric duct during fetal life. It is typically located on the antimesenteric border of the small bowel within 100 cm of the ileocecal valve. Although often lined with ileal mucosa, ectopic gastric, duodenal, colonic, and endometrial mucosa as well as pancreatic tissue, carcinoid tissue, Brunner's glands, and hepatobiliary tissue have been found in Meckel's diverticula.147

Similar to other small bowel diverticula, the majority of Meckel's diverticula are asymptomatic and discovered incidentally at the time of an operation for other indications. Recent reviews indicate that up to 84% of Meckel's diverticula found at operation were asymptomatic. A symptomatic Meckel diverticulum can present in both the pediatric and adult population; the frequency of presentation decreases with increasing age. There is a male predominance (3:1) of both symptomatic and asymptomatic Meckel's diverticula in both the pediatric and adult population.147,149

Symptomatic presentation results from one of many potential complications, including bleeding, obstruction, diverticulitis, perforation, intussusception, ulceration, and rarely the presence of malignancy (carcinoid tumor, sarcoma, stromal tumors, carcinoma, adenocarcinoma, intraductal papillary mucinous adenoma of pancreatic tissue) within the Meckel diverticulum. In the adult population the most common presentations are bleeding (38%), obstruction (34%), and diverticulitis (28%). In the pediatric population the most common presentations are obstruction (40%), bleeding (31%), and diverticulitis (29%).147,149 Obstruction may result from the Meckel diverticulum serving as a lead point for intussusception or volvulus or as a result of an adhesive band to the diverticulum. Bleeding in the setting of a Meckel diverticulum is believed to result from acid secretion from ectopic gastric mucosa leading to ulceration of and subsequent bleeding from adjacent ileal mucosa.

Preoperative diagnosis of a symptomatic Meckel diverticulum can be difficult. A technetium-99m pertechnetate scan is the most common and accurate noninvasive study used to evaluate the presence of a Meckel diverticulum. The tracer used in this study is specific for ectopic gastric mucosa, and thus false-positive results may occur when a duplication cyst containing gastric mucosa is present. Moreover, a Meckel diverticulum can be missed if it does not contain ectopic gastric mucosa. Studies have found technetium-99m pertechnetate scans to be highly sensitive and specific in both the pediatric and adult populations.149–151 In cases of a suspected bleeding, Meckel's diverticulum, angiography, and a tagged RBC scan may be of diagnostic value. If suspicion is high, other etiologies have been ruled out, and noninvasive diagnostic tools exhausted, exploratory laparoscopy may be required to diagnose and treat a complicated Meckel diverticulum.

Surgical resection is indicated for symptomatic Meckel's diverticula. Options for resection include a diverticulectomy or a segmental bowel resection with a primary anastomosis. A diverticulectomy can be performed if amputating the diverticulum at its base will not compromise the ileal lumen. If diverticulitis is present, the line of resection should be free of inflammation. Amputation should be performed in a transverse orientation and can utilize a surgical stapling device. The staple line can then be oversewn with interrupted 3-0 silk Lembert sutures. Alternatively, the diverticulum can be resected between bowel clamps and the defect sutured closed in two layers, using a continuous inner layer of 3-0 Vicryl or chromic suture followed by an outer layer of 3-0 silk Lembert sutures.

In certain cases, simple diverticulectomy is not recommended. Such instances include the presence of diverticulitis or palpable ectopic tissue at the diverticular-intestinal junction.147 In such cases, or if the Meckel diverticulum is associated with ischemia, perforation, or an ulcer in the adjacent intestine, a segmental ileal resection with a primary anastomosis is indicated.

The optimum management of an asymptomatic Meckel diverticulum discovered at laparotomy for a separate indication remains unclear. Some authors argue that certain asymptomatic patients are more likely to develop symptoms and thus recommend resection of an incidentally detected diverticulum in a patient who fulfills any of the following criteria: (1) younger than 50 years, (2) male sex, (3) diverticulum greater than 2 cm in length, and (4) ectopic or abnormal features within a diverticulum.147 A recent review contradicts these findings, however. In this study, the risk of postoperative complications, including infection and intestinal obstruction, was significantly higher following resection than leaving the diverticulum in situ (5.3 vs 1.3%). Moreover, of the 64 patients in this study who did not undergo resection of their asymptomatic Meckel's diverticulum, no patient developed complications with long-term follow-up.148 Another study found the morbidity associated with the resection of an incidental Meckel diverticulum to be higher than that associated with the resection of a symptomatic Meckel diverticulum (20 vs 13%).147 Based on these studies, there is no convincing evidence to recommend resection of a Meckel diverticulum detected incidentally at laparotomy, but it should be considered in certain patient populations.