KEY POINTS ANATOMY AND FUNCTION. 1. Appendectomy for appendicitis is the most commonly performed emergency operation in the world.

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1 Note: Large images and tables on this page may necessitate printing in landscape mode. Copyright The McGraw-Hill Companies. All rights reserved. Schwartz's Principles of Surgery > Chapter 30. The Appendix > KEY POINTS 1. Appendectomy for appendicitis is the most commonly performed emergency operation in the world. 2. Despite the increased use of ultrasonography, computed tomographic scanning, and laparoscopy, the rate of misdiagnosis of appendicitis has remained constant (15.3%), as has the rate of appendiceal rupture. The percentage of misdiagnosed cases of appendicitis is significantly higher among women than among men. 3. Appendicitis is a polymicrobial infection, with some series reporting up to 14 different organisms cultured in patients with perforation. The principal organisms seen in the normal appendix, in acute appendicitis, and in perforated appendicitis are Escherichia coli and Bacteroides fragilis. 4. Antibiotic prophylaxis is effective in the prevention of postoperative wound infection and intra-abdominal abscess. Antibiotic coverage is limited to 24 to 48 hours in cases of nonperforated appendicitis. For perforated appendicitis, 7 to 10 days of treatment is recommended. 5. Compared with younger patients, elderly patients with appendicitis often pose a more difficult diagnostic problem because of the atypical presentation, expanded differential diagnosis, and communication difficulty. These factors contribute to the disproportionately high perforation rate seen in the elderly. 6. The overall incidence of fetal loss after appendectomy is 4% and the risk of early delivery is 7%. Rates of fetal loss are considerably higher in women with complex appendicitis than in those with negative appendectomy and those with simple appendicitis. Removing a normal appendix is associated with a 4% risk of fetal loss and 10% risk of early delivery. 7. Recent data on appendiceal malignancies from the Surveillance, Epidemiology, and End Results program identified mucinous adenocarcinoma as the most frequent histologic diagnosis, followed by adenocarcinoma, carcinoid, goblet cell carcinoma, and signet-ring cell carcinoma. ANATOMY AND FUNCTION The appendix first becomes visible in the eighth week of embryologic development as a protuberance off the terminal portion of the

2 cecum. During both antenatal and postnatal development, the growth rate of the cecum exceeds that of the appendix, so that the appendix is displaced medially toward the ileocecal valve. The relationship of the base of the appendix to the cecum remains constant, whereas the tip can be found in a retrocecal, pelvic, subcecal, preileal, or right pericolic position (Fig. 30-1). These anatomic considerations have significant clinical importance in the context of acute appendicitis. The three taeniae coli converge at the junction of the cecum with the appendix and can be a useful landmark to identify the appendix. The appendix can vary in length from <1 cm to >30 cm; most appendices are 6 to 9 cm long. Appendiceal absence, duplication, and diverticula have all been described. 1 4 Fig

3 Various anatomic positions of the vermiform appendix. For many years, the appendix was erroneously viewed as a vestigial organ with no known function. It is now well recognized that the appendix is an immunologic organ that actively participates in the secretion of immunoglobulins, particularly immunoglobulin A. Although there is no clear role for the appendix in the development of human disease, recent studies demonstrate a potential correlation between

4 appendectomy and the development of inflammatory bowel disease. There appears to be a negative age-related association between prior appendectomy and subsequent development of ulcerative colitis. In addition, comparative analysis clearly shows that prior appendectomy is associated with a more benign phenotype in ulcerative colitis and a delay in onset of disease. The association between Crohn's disease and appendectomy is less clear. Although earlier studies suggested that appendectomy increases the risk of developing Crohn's disease, more recent studies that carefully assessed the timing of appendectomy in relation to the onset of Crohn's disease demonstrated a negative correlation. These data suggest that appendectomy may protect against the subsequent development of inflammatory bowel disease; however, the mechanism is unclear. 4 Lymphoid tissue first appears in the appendix approximately 2 weeks after birth. The amount of lymphoid tissue increases throughout puberty, remains steady for the next decade, and then begins a steady decrease with age. After the age of 60 years, virtually no lymphoid tissue remains within the appendix, and complete obliteration of the appendiceal lumen is common. 1 4 ACUTE APPENDICITIS Historical Background Although ancient texts have scattered descriptions of surgery being undertaken for ailments sounding like appendicitis, credit for performing the first appendectomy goes to Claudius Amyand, a surgeon at St. George's Hospital in London and Sergeant Surgeon to Queen Ann, King George I, and King George II. In 1736, he operated on an 11-year-old boy with a scrotal hernia and a fecal fistula. Within the hernial sac, Amyand found the appendix perforated by a pin. He successfully removed the appendix and repaired the hernia. 5 The appendix was not identified as an organ capable of causing disease until the nineteenth century. In 1824, Louyer-Villermay presented a paper before the Royal Academy of Medicine in Paris. He reported on two autopsy cases of appendicitis and emphasized the importance of the condition. In 1827, François Melier, a French physician, expounded on Louyer-Villermay's work. He reported six autopsy cases and was the first to suggest the antemortem recognition of appendicitis. 5 This work was discounted by many physicians of the era, including Baron Guillaume Dupuytren. Dupuytren believed that inflammation of the cecum was the main cause of pathology of the right lower quadrant. The term typhlitis or perityphlitis was used to describe right lower quadrant inflammation. In 1839, a textbook authored by Bright and Addison entitled Elements of Practical Medicine described the symptoms of appendicitis and identified the primary cause of inflammatory processes of the right lower quadrant. 6 Reginald Fitz, a professor of pathologic anatomy at Harvard, is credited with coining the term appendicitis. His landmark paper definitively identified the appendix as the primary cause of right lower quadrant inflammation. 7 Initial surgical therapy for appendicitis was primarily designed to drain right lower quadrant abscesses that occurred secondary to appendiceal perforation. It appears that the first surgical treatment for appendicitis or perityphlitis without abscess was carried out by Hancock in He incised the peritoneum and drained the right lower quadrant without removing the appendix. The first published

5 account of appendectomy for appendicitis was by Krönlein in However, this patient died 2 days after operation. Fergus, in Canada, performed the first elective appendectomy in The greatest contributor to the advancement in the treatment of appendicitis was Charles McBurney. In 1889, he published his landmark paper in the New York State Medical Journal describing the indications for early laparotomy for the treatment of appendicitis. It is in this paper that he described the McBurney point as follows: "maximum tenderness, when one examines with the fingertips is, in adults, one half to two inches inside the right anterior spinous process of the ilium on a line drawn to the umbilicus." 8 McBurney subsequently published a paper in 1894 describing the incision that bears his name. 9 However, McBurney later credited McArthur with first describing this incision. Semm is widely credited with performing the first successful laparoscopic appendectomy in The surgical treatment of appendicitis is one of the great public health advances of the last 150 years. Appendectomy for appendicitis is the most commonly performed emergency operation in the world. Appendicitis is a disease of the young, with 40% of cases occurring in patients between the ages of 10 and 29 years. 11 In 1886, Fitz reported the associated mortality rate of appendicitis to be at least 67% without surgical therapy. 7 Currently, the mortality rate for acute appendicitis with treatment is reported to be <1%. 12 Incidence The lifetime rate of appendectomy is 12% for men and 25% for women, with approximately 7% of all people undergoing appendectomy for acute appendicitis during their lifetime. Over the 10-year period from 1987 to 1997, the overall appendectomy rate decreased in parallel with a decrease in incidental appendectomy. 11,13 However, the rate of appendectomy for appendicitis has remained constant at 10 per 10,000 patients per year. 14 Appendicitis is most frequently seen in patients in their second through fourth decades of life, with a mean age of 31.3 years and a median age of 22 years. There is a slight male:female predominance (1.2 to 1.3:1). 11,13 Despite the increased use of ultrasonography, computed tomography (CT), and laparoscopy, the rate of misdiagnosis of appendicitis has remained constant (15.3%), as has the rate of appendiceal rupture. The percentage of misdiagnosed cases of appendicitis is significantly higher among women than among men (22.2 vs. 9.3%). The negative appendectomy rate for women of reproductive age is 23.2%, with the highest rates in women aged 40 to 49 years. The highest negative appendectomy rate is reported for women >80 years of age (Fig. 30-2). 13,14 Fig

6 Rate of negative appendectomy by age group. (Adapted from Flum et al. 13,14 ) Etiology and Pathogenesis Obstruction of the lumen is the dominant etiologic factor in acute appendicitis. Fecaliths are the most common cause of appendiceal obstruction. Less common causes are hypertrophy of lymphoid tissue, inspissated barium from previous x-ray studies, tumors, vegetable and fruit seeds, and intestinal parasites. The frequency of obstruction rises with the severity of the inflammatory process. Fecaliths are found in 40% of cases of simple acute appendicitis, in 65% of cases of gangrenous appendicitis without rupture, and in nearly 90% of cases of gangrenous appendicitis with rupture. Traditionally the belief has been that there is a predictable sequence of events leading to eventual appendiceal rupture. The proximal

7 obstruction of the appendiceal lumen produces a closed-loop obstruction, and continuing normal secretion by the appendiceal mucosa rapidly produces distention. The luminal capacity of the normal appendix is only 0.1 ml. Secretion of as little as 0.5 ml of fluid distal to an obstruction raises the intraluminal pressure to 60 cm H 2 O. Distention of the appendix stimulates the nerve endings of visceral afferent stretch fibers, producing vague, dull, diffuse pain in the midabdomen or lower epigastrium. Peristalsis also is stimulated by the rather sudden distention, so that some cramping may be superimposed on the visceral pain early in the course of appendicitis. Distention increases from continued mucosal secretion and from rapid multiplication of the resident bacteria of the appendix. Distention of this magnitude usually causes reflex nausea and vomiting, and the diffuse visceral pain becomes more severe. As pressure in the organ increases, venous pressure is exceeded. Capillaries and venules are occluded, but arteriolar inflow continues, resulting in engorgement and vascular congestion. The inflammatory process soon involves the serosa of the appendix and in turn parietal peritoneum in the region, which produces the characteristic shift in pain to the right lower quadrant. The mucosa of the GI tract, including the appendix, is susceptible to impairment of blood supply; thus its integrity is compromised early in the process, which allows bacterial invasion. As progressive distention encroaches on first the venous return and subsequently the arteriolar inflow, the area with the poorest blood supply suffers most: ellipsoidal infarcts develop in the antimesenteric border. As distention, bacterial invasion, compromise of vascular supply, and infarction progress, perforation occurs, usually through one of the infarcted areas on the antimesenteric border. Perforation generally occurs just beyond the point of obstruction rather than at the tip because of the effect of diameter on intraluminal tension. This sequence is not inevitable, however, and some episodes of acute appendicitis apparently subside spontaneously. Many patients who are found at operation to have acute appendicitis give a history of previous similar, but less severe, attacks of right lower quadrant pain. Pathologic examination of the appendices removed from these patients often reveals thickening and scarring, suggesting old, healed acute inflammation. 15,16 The strong association between delay in presentation and appendiceal perforation supported the proposition that appendiceal perforation is the advanced stage of acute appendicitis; however, recent epidemiologic studies have suggested that nonperforated and perforated appendicitis may, in fact, be different diseases. 17 Bacteriology The bacterial population of the normal appendix is similar to that of the normal colon. The appendiceal flora remains constant throughout life with the exception of Porphyromonas gingivalis. This bacterium is seen only in adults. 18 The bacteria cultured in cases of appendicitis are therefore similar to those seen in other colonic infections such as diverticulitis. The principal organisms seen in the normal appendix, in acute appendicitis, and in perforated appendicitis are Escherichia coli and Bacteroides fragilis However, a wide variety of both facultative and anaerobic bacteria and mycobacteria may be present (Table 30-1). Appendicitis is a polymicrobial infection, with some series reporting the culture of up to 14 different organisms in patients with perforation. 18

8 Table 30-1 Common Organisms Seen in Patients with Acute Appendicitis Aerobic and Facultative Gram-negative bacilli Escherichia coli Pseudomonas aeruginosa Klebsiella species Gram-positive cocci Streptococcus anginosus Other Streptococcus species Enterococcus species Anaerobic Gram-negative bacilli Bacteroides fragilis Other Bacteroides species Fusobacterium species Gram-positive cocci Peptostreptococcus species Gram-positive bacilli Clostridium species The routine culture of intraperitoneal samples in patients with either perforated or nonperforated appendicitis is questionable. As discussed earlier, the flora is known, and therefore broad-spectrum antibiotics are indicated. By the time culture results are available, the patient often has recovered from the illness. In addition, the number of organisms cultured and the ability of a specific laboratory to culture anaerobic organisms vary greatly. Peritoneal culture should be reserved for patients who are immunosuppressed, as a result of either illness or medication, and for patients who develop an abscess after the treatment of appendicitis Antibiotic prophylaxis is effective in the prevention of postoperative wound infection and intra-abdominal abscess. 23 Antibiotic coverage is limited to 24 to 48 hours in cases of nonperforated appendicitis. For perforated appendicitis, 7 to 10 days of therapy is recommended. IV antibiotics are usually given until the white blood cell count is normal and the patient is afebrile for 24 hours. Antibiotic irrigation of the peritoneal cavity and the use of transperitoneal drainage through the wound are controversial. 24 Clinical Manifestations SYMPTOMS Abdominal pain is the prime symptom of acute appendicitis. Classically, pain is initially diffusely centered in the lower epigastrium or umbilical area, is moderately severe, and is steady, sometimes with intermittent cramping superimposed. After a period varying from 1

9 to 12 hours, but usually within 4 to 6 hours, the pain localizes to the right lower quadrant. This classic pain sequence, although usual, is not invariable. In some patients, the pain of appendicitis begins in the right lower quadrant and remains there. Variations in the anatomic location of the appendix account for many of the variations in the principal locus of the somatic phase of the pain. For example, a long appendix with the inflamed tip in the left lower quadrant causes pain in that area. A retrocecal appendix may cause principally flank or back pain; a pelvic appendix, principally suprapubic pain; and a retroileal appendix, testicular pain, presumably from irritation of the spermatic artery and ureter. Intestinal malrotation also is responsible for puzzling pain patterns. The visceral component is in the normal location, but the somatic component is felt in that part of the abdomen where the cecum has been arrested in rotation. Anorexia nearly always accompanies appendicitis. It is so constant that the diagnosis should be questioned if the patient is not anorectic. Although vomiting occurs in nearly 75% of patients, it is neither prominent nor prolonged, and most patients vomit only once or twice. Vomiting is caused by both neural stimulation and the presence of ileus. Most patients give a history of obstipation beginning before the onset of abdominal pain, and many feel that defecation would relieve their abdominal pain. Diarrhea occurs in some patients, however, particularly children, so that the pattern of bowel function is of little differential diagnostic value. The sequence of symptom appearance has great significance for the differential diagnosis. In >95% of patients with acute appendicitis, anorexia is the first symptom, followed by abdominal pain, which is followed, in turn, by vomiting (if vomiting occurs). If vomiting precedes the onset of pain, the diagnosis of appendicitis should be questioned. SIGNS Physical findings are determined principally by what the anatomic position of the inflamed appendix is, as well as by whether the organ has already ruptured when the patient is first examined. Vital signs are minimally changed by uncomplicated appendicitis. Temperature elevation is rarely >1 C (1.8 F) and the pulse rate is normal or slightly elevated. Changes of greater magnitude usually indicate that a complication has occurred or that another diagnosis should be considered. 25 Patients with appendicitis usually prefer to lie supine, with the thighs, particularly the right thigh, drawn up, because any motion increases pain. If asked to move, they do so slowly and with caution. The classic right lower quadrant physical signs are present when the inflamed appendix lies in the anterior position. Tenderness often is maximal at or near the McBurney point. 8 Direct rebound tenderness usually is present. In addition, referred or indirect rebound tenderness is present. This referred tenderness is felt maximally in the right lower quadrant, which indicates localized peritoneal irritation. 25 The Rovsing sign pain in the right lower quadrant when palpatory pressure is exerted in the left lower quadrant also

10 indicates the site of peritoneal irritation. Cutaneous hyperesthesia in the area supplied by the spinal nerves on the right at T10, T11, and T12 frequently accompanies acute appendicitis. In patients with obvious appendicitis, this sign is superfluous, but in some early cases, it may be the first positive sign. Hyperesthesia is elicited either by needle prick or by gently picking up the skin between the forefinger and thumb. Muscular resistance to palpation of the abdominal wall roughly parallels the severity of the inflammatory process. Early in the disease, resistance, if present, consists mainly of voluntary guarding. As peritoneal irritation progresses, muscle spasm increases and becomes largely involuntary, that is, true reflex rigidity due to contraction of muscles directly beneath the inflamed parietal peritoneum. Anatomic variations in the position of the inflamed appendix lead to deviations in the usual physical findings. With a retrocecal appendix, the anterior abdominal findings are less striking, and tenderness may be most marked in the flank. When the inflamed appendix hangs into the pelvis, abdominal findings may be entirely absent, and the diagnosis may be missed unless the rectum is examined. As the examining finger exerts pressure on the peritoneum of Douglas' cul-de-sac, pain is felt in the suprapubic area as well as locally within the rectum. Signs of localized muscle irritation also may be present. The psoas sign indicates an irritative focus in proximity to that muscle. The test is performed by having the patient lie on the left side as the examiner slowly extends the patient's right thigh, thus stretching the iliopsoas muscle. The test result is positive if extension produces pain. Similarly, a positive obturator sign of hypogastric pain on stretching the obturator internus indicates irritation in the pelvis. The test is performed by passive internal rotation of the flexed right thigh with the patient supine. LABORATORY FINDINGS Mild leukocytosis, ranging from 10,000 to 18,000 cells/mm 3, usually is present in patients with acute, uncomplicated appendicitis and often is accompanied by a moderate polymorphonuclear predominance. White blood cell counts are variable, however. It is unusual for the white blood cell count to be >18,000 cells/mm 3 in uncomplicated appendicitis. White blood cell counts above this level raise the possibility of a perforated appendix with or without an abscess. Urinalysis can be useful to rule out the urinary tract as the source of infection. Although several white or red blood cells can be present from ureteral or bladder irritation as a result of an inflamed appendix, bacteriuria in a urine specimen obtained via catheter generally is not seen in acute appendicitis. 26 Imaging Studies Plain films of the abdomen, although frequently obtained as part of the general evaluation of a patient with an acute abdomen, rarely are helpful in diagnosing acute appendicitis. However, plain radiographs can be of significant benefit in ruling out other pathology. In patients with acute appendicitis, one often sees an abnormal bowel gas pattern, which is a nonspecific finding. The presence of a fecalith is rarely noted on plain films but, if present, is highly suggestive of the diagnosis. A chest radiograph is sometimes indicated to rule out referred pain from a right lower lobe pneumonic process.

11 Additional radiographic studies include barium enema examination and radioactively labeled leukocyte scans. If the appendix fills on barium enema, appendicitis is excluded. On the other hand, if the appendix does not fill, no determination can be made. 27 To date, there has not been enough experience with radionuclide scans to assess their utility. Graded compression sonography has been suggested as an accurate way to establish the diagnosis of appendicitis. The technique is inexpensive, can be performed rapidly, does not require a contrast medium, and can be used even in pregnant patients. Sonographically, the appendix is identified as a blind-ending, nonperistaltic bowel loop originating from the cecum. With maximal compression, the diameter of the appendix is measured in the anteroposterior dimension. Scan results are considered positive if a noncompressible appendix 6 mm in the anteroposterior direction is demonstrated (Fig. 30-3). The presence of an appendicolith establishes the diagnosis. Thickening of the appendiceal wall and the presence of periappendiceal fluid is highly suggestive. Sonographic demonstration of a normal appendix, which is an easily compressible, blind-ending tubular structure measuring 5 mm in diameter, excludes the diagnosis of acute appendicitis. The study results are considered inconclusive if the appendix is not visualized and there is no pericecal fluid or mass. When the diagnosis of acute appendicitis is excluded by sonography, a brief survey of the remainder of the abdominal cavity should be performed to establish an alternative diagnosis. In females of childbearing age, the pelvic organs must be adequately visualized either by transabdominal or endovaginal ultrasonography to exclude gynecologic pathology as a cause of acute abdominal pain. The sonographic diagnosis of acute appendicitis has a reported sensitivity of 55 to 96% and a specificity of 85 to 98% Sonography is similarly effective in children and pregnant women, although its application is somewhat limited in late pregnancy. Fig

12

13 Sonogram of a 10-year-old girl who presented with nausea, vomiting, and abdominal pain. The appendix measured 10.0 mm in maximal anteroposterior diameter in both the noncompression (A) and compression (B) views. Although sonography can easily identify abscesses in cases of perforation, the technique has limitations and results are user dependent.

14 A false-positive scan result can occur in the presence of periappendicitis from surrounding inflammation, a dilated fallopian tube can be mistaken for an inflamed appendix, inspissated stool can mimic an appendicolith, and, in obese patients, the appendix may not be compressible because of overlying fat. False-negative sonogram results can occur if appendicitis is confined to the appendiceal tip, the appendix is retrocecal, the appendix is markedly enlarged and mistaken for small bowel, or the appendix is perforated and therefore compressible. 31 Some studies have reported that graded compression sonography improved the diagnosis of appendicitis over clinical examination, specifically decreasing the percentage of negative explorations for appendectomies from 37 to 13%. 32 Sonography also decreases the time before operation. Sonography identified appendicitis in 10% of patients who were believed to have a low likelihood of the disease on physical examination. 33 The positive and negative predictive values of ultrasonography have impressively been reported as 91 and 92%, respectively. However, in a recent prospective multicenter study, routine ultrasonography did not improve diagnostic accuracy or rates of negative appendectomy or perforation compared with clinical assessment. High-resolution helical CT also has been used to diagnose appendicitis. On CT scan, the inflamed appendix appears dilated (>5 cm) and the wall is thickened. There is usually evidence of inflammation, with "dirty fat," thickened mesoappendix, and even an obvious phlegmon (Fig. 30-4). Fecaliths can be easily visualized, but their presence is not necessarily pathognomonic of appendicitis. An important suggestive abnormality is the arrowhead sign. This is caused by thickening of the cecum, which funnels contrast agent toward the orifice of the inflamed appendix. CT scanning is also an excellent technique for identifying other inflammatory processes masquerading as appendicitis. Fig

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16 Computed tomographic scans with findings positive for appendicitis. Note the thick-walled and dilated appendix (A) and mesenteric streaking and "dirty fat" (B). Several CT techniques have been used, including focused and nonfocused CT scans and enhanced and nonenhanced helical CT scanning. Nonenhanced helical CT scanning is important, because one of the disadvantages of using CT scanning in the evaluation of right lower quadrant pain is dye allergy. Surprisingly, all of these techniques have yielded essentially identical rates of diagnostic accuracy: 92 to 97% sensitivity, 85 to 94% specificity, 90 to 98% accuracy, and 75 to 95% positive and 95 to 99% negative predictive values The additional use of a rectally administered contrast agent did not improve the results of CT scanning. A number of studies have documented improvement in diagnostic accuracy with the liberal use of CT scanning in the work-up of

17 suspected appendicitis. CT lowered the rate of negative appendectomies from 19 to 12% in one study, 37 and the incidence of negative appendectomies in women from 24 to 5% in another. 38 The use of this imaging study altered the care of 24% of patients studied and provided alternative diagnoses in half of the patients with normal appendices on CT scan. 39 Despite the potential usefulness of this technique, there are significant disadvantages. CT scanning is expensive, exposes the patient to significant radiation, and cannot be used during pregnancy. Allergy contraindicates the administration of IV contrast agents in some patients, and others cannot tolerate the oral ingestion of luminal dye, particularly in the presence of nausea and vomiting. Finally, not all studies have documented the utility of CT scanning in all patients with right lower quadrant pain. 40 A number of studies have compared the effectiveness of graded compression sonography and helical CT in establishing the diagnosis of appendicitis. Although the differences are rather small, CT scanning has consistently proven superior. For example, in one study, 600 ultrasounds and 317 CT scans demonstrated sensitivity of 80 and 97%, specificity of 93 and 94%, diagnostic accuracy of 89 and 95%, positive predictive value of 91 and 92%, and negative predictive value of 88 and 98%, respectively. 30 In another study, ultrasound positively impacted the management of 19% of patients, compared with 73% of patients for CT. Finally, in a third study, the negative appendix rate was 17% for patients studied by ultrasonography compared with a negative appendix rate of 2% for patients who underwent helical CT scanning. 41 One concern about ultrasonography is the high intraobserver variability. 42 One issue that has not been resolved is which patients are candidates for imaging studies. 43 This question may be moot, because CT scanning routinely is ordered by emergency physicians before surgeons are even consulted. The concept that all patients with right lower quadrant pain should undergo CT scanning has been strongly supported by two reports by Rao and his colleagues at the Massachusetts General Hospital. In one, this group documented that CT scanning led to a fall in the negative appendectomy rate from 20 to 7% and a decline in the perforation rate from 22 to 14%, as well as establishment of an alternative diagnosis in 50% of patients. 44 In the second study, published in the New England Journal of Medicine, Rao and associates documented that CT scanning prevented 13 unnecessary appendectomies, saved 50 inpatient hospital days, and lowered the per-patient cost by $ In contrast, several other studies failed to prove an advantage of routine CT scanning, documenting that surgeon accuracy approached that of the imaging study and expressing concern that the imaging studies could adversely delay appendectomy in affected patients. 46,47 The rational approach is the selective use of CT scanning. This has been documented by several studies in which imaging was performed based on an algorithm or protocol. 48 The likelihood of appendicitis can be ascertained using the Alvarado scale (Table 30-2). 49 This scoring system was designed to improve the diagnosis of appendicitis and was devised by giving relative weight to specific clinical manifestation. Table 30-2 lists the eight specific indicators identified. Patients with scores of 9 or 10 are almost certain to have appendicitis; there is little advantage in further work-up, and they should go to the operating room. Patients with scores of 7 or 8 have a high likelihood of appendicitis, whereas scores of 5 or 6 are compatible with, but not diagnostic of, appendicitis. CT scanning is certainly appropriate for patients with Alvarado scores of 5 and 6, and a case can be built for imaging for those with scores of 7 and 8. On the

18 other hand, it is difficult to justify the expense, radiation exposure, and possible complications of CT scanning in patients whose scores of 0 to 4 make it extremely unlikely (but not impossible) that they have appendicitis. Table 30-2 Alvarado Scale for the Diagnosis of Appendicitis Manifestations Value Symptoms Migration of pain 1 Anorexia 1 Nausea and/or vomiting 1 Signs Right lower quadrant tenderness 2 Rebound 1 Elevated temperature 1 Laboratory values Leukocytosis 2 Left shift in leukocyte count 1 Total points 10 Source: Reproduced with permission from Alvarado. 49 Selective CT scanning based on the likelihood of appendicitis takes advantage of the clinical skill of the experienced surgeon and, when indicated, adds the expertise of the radiologist and his or her imaging study. Figure 30-5 proposes a treatment algorithm addressing the rational use of diagnostic testing. 50 Fig

19 Clinical algorithm for suspected cases of acute appendicitis. If gynecologic disease is suspected, a pelvic and endovaginal ultrasound examination is indicated. (Reproduced with permission from Paulson et al. 50 Copyright Massachusetts Medical Society. All rights reserved.) Laparoscopy can serve as both a diagnostic and therapeutic maneuver for patients with acute abdominal pain and suspected acute appendicitis. Laparoscopy is probably most useful in the evaluation of females with lower abdominal complaints, because appendectomy is performed on a normal appendix in as many as 30 to 40% of these patients. Differentiating acute gynecologic pathology from acute appendicitis can be effectively accomplished using the laparoscope. Appendiceal Rupture

20 Immediate appendectomy has long been the recommended treatment for acute appendicitis because of the presumed risk of progression to rupture. The overall rate of perforated appendicitis is 25.8%. Children <5 years of age and patients >65 years of age have the highest rates of perforation (45 and 51%, respectively) (Fig. 30-6). 14,15,51 It has been suggested that delays in presentation are responsible for the majority of perforated appendices. There is no accurate way of determining when and if an appendix will rupture before resolution of the inflammatory process. Recent studies suggest that, in selected patients, observation and antibiotic therapy alone may be an appropriate treatment for acute appendicitis. 17,52 Fig Rate of appendiceal rupture by age group.

21 (Personal communication from David Flum, MD.) Appendiceal rupture occurs most frequently distal to the point of luminal obstruction along the antimesenteric border of the appendix. Rupture should be suspected in the presence of fever with a temperature of >39 C (102 F) and a white blood cell count of >18,000 cells/mm 3. In the majority of cases, rupture is contained and patients display localized rebound tenderness. Generalized peritonitis will be present if the walling-off process is ineffective in containing the rupture. In 2 to 6% of cases, an ill-defined mass is detected on physical examination. This could represent a phlegmon, which consists of matted loops of bowel adherent to the adjacent inflamed appendix, or a periappendiceal abscess. Patients who present with a mass have experienced symptoms for a longer duration, usually at least 5 to 7 days. Distinguishing acute, uncomplicated appendicitis from acute appendicitis with perforation on the basis of clinical findings is often difficult, but it is important to make the distinction because their treatment differs. CT scan may be beneficial in guiding therapy. Phlegmons and small abscesses can be treated conservatively with IV antibiotics; well-localized abscesses can be managed with percutaneous drainage; complex abscesses should be considered for surgical drainage. If operative drainage is required, it should be performed using an extraperitoneal approach, with appendectomy reserved for cases in which the appendix is easily accessible. Interval appendectomy performed at least 6 weeks after the acute event has classically been recommended for all patients treated either nonoperatively or with simple drainage of an abscess. 53,54 Differential Diagnosis The differential diagnosis of acute appendicitis is essentially the diagnosis of the acute abdomen (see Chap. 35). This is because clinical manifestations are not specific for a given disease but are specific for disturbance of a given physiologic function or functions. Thus, an essentially identical clinical picture can result from a wide variety of acute processes within the peritoneal cavity that produce the same alterations of function as does acute appendicitis. The accuracy of preoperative diagnosis should be approximately 85%. If it is consistently less, it is likely that some unnecessary operations are being performed, and a more rigorous preoperative differential diagnosis is in order. A diagnostic accuracy rate that is consistently >90% should also cause concern, because this may mean that some patients with atypical, but bona fide, cases of acute appendicitis are being "observed" when they should receive prompt surgical intervention. The Haller group, however, has shown that this is not invariably true. 55 Before that group's study, the perforation rate at the hospital at which the study took place was 26.7%, and acute appendicitis was found in 80% of the patients undergoing operation. By implementing a policy of intensive inhospital observation when the diagnosis of appendicitis was unclear, the group raised the rate of acute appendicitis found at operation to 94%, but the perforation rate remained unchanged at 27.5%. 55 The rate of false-negative appendectomies is highest in young adult females. A normal appendix is found in 32 to 45% of appendectomies performed in women 15 to 45 years of age. 14 A common error is to make a preoperative diagnosis of acute appendicitis only to find some other condition (or nothing) at operation.

22 Much less frequently, acute appendicitis is found after a preoperative diagnosis of another condition. The most common erroneous preoperative diagnoses together accounting for >75% of cases are, in descending order of frequency, acute mesenteric lymphadenitis, no organic pathologic condition, acute pelvic inflammatory disease, twisted ovarian cyst or ruptured graafian follicle, and acute gastroenteritis. The differential diagnosis of acute appendicitis depends on four major factors: the anatomic location of the inflamed appendix; the stage of the process (i.e., simple or ruptured); the patient's age; and the patient's sex ACUTE MESENTERIC ADENITIS Acute mesenteric adenitis is the disease most often confused with acute appendicitis in children. Almost invariably, an upper respiratory tract infection is present or has recently subsided. The pain usually is diffuse, and tenderness is not as sharply localized as in appendicitis. Voluntary guarding is sometimes present, but true rigidity is rare. Generalized lymphadenopathy may be noted. Laboratory procedures are of little help in arriving at the correct diagnosis, although a relative lymphocytosis, when present, suggests mesenteric adenitis. Observation for several hours is in order if the diagnosis of mesenteric adenitis seems likely, because it is a self-limited disease. However, if the differentiation remains in doubt, immediate exploration is the safest course of action. Human infection with Yersinia enterocolitica or Yersinia pseudotuberculosis, transmitted through food contaminated by feces or urine, causes mesenteric adenitis as well as ileitis, colitis, and acute appendicitis. Many of the infections are mild and self limited, but they may lead to systemic disease with a high fatality rate if untreated. The organisms are usually sensitive to tetracyclines, streptomycin, ampicillin, and kanamycin. A preoperative suspicion of the diagnosis should not delay operative intervention, because appendicitis caused by Yersinia cannot be clinically distinguished from appendicitis due to other causes. Approximately 6% of cases of mesenteric adenitis are caused by Yersinia infection. Salmonella typhimurium infection causes mesenteric adenitis and paralytic ileus with symptoms similar to those of appendicitis. The diagnosis can be established by serologic testing. Campylobacter jejuni causes diarrhea and pain that mimics that of appendicitis. The organism can be cultured from stool. GYNECOLOGIC DISORDERS Diseases of the female internal reproductive organs that may erroneously be diagnosed as appendicitis are, in approximate descending order of frequency, pelvic inflammatory disease, ruptured graafian follicle, twisted ovarian cyst or tumor, endometriosis, and ruptured ectopic pregnancy. Pelvic Inflammatory Disease In pelvic inflammatory disease the infection usually is bilateral but, if confined to the right tube, may mimic acute appendicitis. Nausea

23 and vomiting are present in patients with appendicitis, but in only approximately 50% of those with pelvic inflammatory disease. Pain and tenderness are usually lower, and motion of the cervix is exquisitely painful. Intracellular diplococci may be demonstrable on smear of the purulent vaginal discharge. The ratio of cases of appendicitis to cases of pelvic inflammatory disease is low in females in the early phase of the menstrual cycle and high during the luteal phase. The careful clinical use of these features has reduced the incidence of negative findings on laparoscopy in young women to 15%. Ruptured Graafian Follicle Ovulation commonly results in the spillage of sufficient amounts of blood and follicular fluid to produce brief, mild lower abdominal pain. If the amount of fluid is unusually copious and is from the right ovary, appendicitis may be simulated. Pain and tenderness are rather diffuse. Leukocytosis and fever are minimal or absent. Because this pain occurs at the midpoint of the menstrual cycle, it is often called mittelschmerz. Twisted Ovarian Cyst Serous cysts of the ovary are common and generally remain asymptomatic. When right-sided cysts rupture or undergo torsion, the manifestations are similar to those of appendicitis. Patients develop right lower quadrant pain, tenderness, rebound, fever, and leukocytosis. If the mass is palpable on physical examination, the diagnosis can be made easily. Both transvaginal ultrasonography and CT scanning can be diagnostic if a mass is not palpable. Torsion requires emergent operative treatment. If the torsion is complete or longstanding, the pedicle undergoes thrombosis, and the ovary and tube become gangrenous and require resection. Leakage of ovarian cysts resolves spontaneously, however, and is best treated nonoperatively. 24,56 61 Ruptured Ectopic Pregnancy Blastocysts may implant in the fallopian tube (usually the ampullary portion) and in the ovary. Rupture of right tubal or ovarian pregnancies can mimic appendicitis. Patients may give a history of abnormal menses, either missing one or two periods or noting only slight vaginal bleeding. Unfortunately, patients do not always realize they are pregnant. The development of right lower quadrant or pelvic pain may be the first symptom. The diagnosis of ruptured ectopic pregnancy should be relatively easy. The presence of a pelvic mass and elevated levels of chorionic gonadotropin are characteristic. Although the leukocyte count rises slightly (to approximately 14,000 cells/mm 3 ), the hematocrit level falls as a consequence of the intra-abdominal hemorrhage. Vaginal examination reveals cervical motion and adnexal tenderness, and a more definitive diagnosis can be established by culdocentesis. The presence of blood and particularly decidual tissue is pathognomonic. The treatment of ruptured ectopic pregnancy is emergency surgery. ACUTE GASTROENTERITIS

24 Acute gastroenteritis is common but usually can be easily distinguished from acute appendicitis. Gastroenteritis is characterized by profuse diarrhea, nausea, and vomiting. Hyperperistaltic abdominal cramps precede the watery stools. The abdomen is relaxed between cramps, and there are no localizing signs. Laboratory values vary with the specific cause. OTHER INTESTINAL DISORDERS Meckel's Diverticulitis Meckel's diverticulitis gives rise to a clinical picture similar to that of acute appendicitis. Meckel's diverticulum is located within the distal 2 ft of the ileum. Meckel's diverticulitis is associated with the same complications as appendicitis and requires the same treatment prompt surgical intervention. Resection of the segment of ileum bearing the diverticulum with end-to-end anastomosis can nearly always be done through a McBurney incision, extended if necessary, or laparoscopically. Crohn's Enteritis The manifestations of acute regional enteritis fever, right lower quadrant pain and tenderness, and leukocytosis often simulate acute appendicitis. The presence of diarrhea and the absence of anorexia, nausea, and vomiting favor a diagnosis of enteritis, but this is not sufficient to exclude acute appendicitis. In an appreciable percentage of patients with chronic regional enteritis, the diagnosis is first made at the time of operation for presumed acute appendicitis. In cases of an acutely inflamed distal ileum with no cecal involvement and a normal appendix, appendectomy is indicated. Progression to chronic Crohn's ileitis is uncommon. Colonic Lesions Diverticulitis or perforating carcinoma of the cecum, or of that portion of the sigmoid that lies in the right side, may be impossible to distinguish from appendicitis. These entities should be considered in older patients. CT scanning is often helpful in making a diagnosis in older patients with right lower quadrant pain and atypical clinical presentations. Epiploic appendagitis probably results from infarction of the colonic appendage(s) secondary to torsion. Symptoms may be minimal, or there may be continuous abdominal pain in an area corresponding to the contour of the colon, lasting several days. Pain shift is unusual, and there is no diagnostic sequence of symptoms. The patient does not look ill, nausea and vomiting are unusual, and appetite generally is unaffected. Localized tenderness over the site is usual and often is associated with rebound without rigidity. In 25% of reported cases, pain persists or recurs until the infarcted epiploic appendage is removed. OTHER DISEASES Diseases or conditions not mentioned in the preceding sections that must be considered in the differential diagnosis include foreign body perforations of the bowel, closed-loop intestinal obstruction, mesenteric vascular infarction, pleuritis of the right lower chest, acute cholecystitis, acute pancreatitis, hematoma of the abdominal wall, epididymitis, testicular torsion, urinary tract infection, ureteral stone,

25 primary peritonitis, and Henoch-Schönlein purpura. Acute Appendicitis in the Young The establishment of a diagnosis of acute appendicitis is more difficult in young children than in the adult. The inability of young children to give an accurate history, diagnostic delays by both parents and physicians, and the frequency of GI upset in children are all contributing factors. 62 In children the physical examination findings of maximal tenderness in the right lower quadrant, the inability to walk or walking with a limp, and pain with percussion, coughing, and hopping were found to have the highest sensitivity for appendicitis. 63 The more rapid progression to rupture and the inability of the underdeveloped greater omentum to contain a rupture lead to significant morbidity rates in children. Children <5 years of age have a negative appendectomy rate of 25% and an appendiceal perforation rate of 45%. These rates may be compared with a negative appendectomy rate of <10% and a perforated appendix rate of 20% for children 5 to 12 years of age. 13,14 The incidence of major complications after appendectomy in children is correlated with appendiceal rupture. The wound infection rate after the treatment of nonperforated appendicitis in children is 2.8% compared with a rate of 11% after the treatment of perforated appendicitis. The incidence of intra-abdominal abscess also is higher after the treatment of perforated appendicitis than after nonperforated appendicitis (6% vs. 3%). 23 The treatment regimen for perforated appendicitis generally includes immediate appendectomy and irrigation of the peritoneal cavity. Antibiotic coverage is limited to 24 to 48 hours in cases of nonperforated appendicitis. For perforated appendicitis IV antibiotics usually are given until the white blood cell count is normal and the patient is afebrile for 24 hours. The use of antibiotic irrigation of the peritoneal cavity and transperitoneal drainage through the wound are controversial. Laparoscopic appendectomy has been shown to be safe and effective for the treatment of appendicitis in children. 64 Acute Appendicitis in the Elderly Compared with younger patients, elderly patients with appendicitis often pose a more difficult diagnostic problem because of the atypical presentation, expanded differential diagnosis, and communication difficulty. These factors may be responsible for the disproportionately high perforation rate seen in the elderly. In the general population, perforation rates range from 20 to 30%, compared with 50 to 70% in the elderly. 65 In addition, the perforation rate appears to increase with age >80 years. 66 Elderly patients usually present with lower abdominal pain, but on clinical examination, localized right lower quadrant tenderness is present in only 80 to 90% of patients. A history of periumbilical pain migrating to the right lower quadrant is reported infrequently. The usefulness of the Alvarado score appears to decline in the elderly. Fewer then 50% of the elderly with appendicitis have an Alvarado score of Although currently there are no criteria that definitively identify elderly patients with acute appendicitis who are at risk of rupture, prioritization should be given to patients with a temperature of >38 C (100.4 F) and a shift to the left in leukocyte count of >76%, especially if they are male, are anorectic, or have had pain of long duration before admission. 65