Download KEY POINTS ANATOMY AND FUNCTION

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
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. 30-1.
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
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 1848. He incised the peritoneum and drained the right lower quadrant without removing the appendix. The first published
account of appendectomy for appendicitis was by Krönlein in 1886. However, this patient died 2 days after operation. Fergus, in Canada,
performed the first elective appendectomy in 1883.5
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 1982.10
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. 30-2.
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
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 H2O. 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.18–21 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
Table 30-1 Common Organisms Seen in Patients with Acute Appendicitis
Aerobic and Facultative
Anaerobic
Gram-negative bacilli
Gram-negative bacilli
Escherichia coli
Bacteroides fragilis
Pseudomonas aeruginosa
Other Bacteroides species
Klebsiella species
Fusobacterium species
Gram-positive cocci
Streptococcus anginosus
Other Streptococcus species
Enterococcus 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.20–22 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
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
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/mm3, 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/mm3 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.
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%.28–30 Sonography is similarly effective in children and pregnant women, although its application is somewhat limited in late
pregnancy.
Fig. 30-3.
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.
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. 30-4.
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.34–36 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
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 $447.45 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
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
Symptoms
Signs
Laboratory values
Manifestations
Value
Migration of pain
1
Anorexia
1
Nausea and/or vomiting
1
Right lower quadrant tenderness
2
Rebound
1
Elevated temperature
1
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. 30-5.
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
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. 30-6.
Rate of appendiceal rupture by age group.
(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/mm3. 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.
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.56–60
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
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/mm3), 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
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,
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 ≥7.66 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
As a result of increased comorbidities and an increased rate of perforation, postoperative morbidity, mortality, and hospital length of
stay are increased in the elderly compared with younger populations with appendicitis. Although no randomized trials have been
conducted, it appears that elderly patients benefit from a laparoscopic approach to treatment of appendicitis. The use of laparoscopy in
the elderly has significantly increased in recent years. In general, laparoscopic appendectomy offers elderly patients with appendicitis a
shorter length of hospital stay, a reduction in complication and mortality rates, and a greater chance of discharge to home (independent
of further nursing care or rehabilitation).67
Acute Appendicitis during Pregnancy
Appendectomy for presumed appendicitis is the most common surgical emergency during pregnancy. The incidence is approximately 1 in
766 births. Acute appendicitis can occur at any time during pregnancy.68 The overall negative appendectomy rate during pregnancy is
approximately 25% and appears to be higher than the rate seen in nonpregnant women.68,69 A higher rate of negative appendectomy is
seen in the second trimester, and the lowest rate is in the third trimester. The diversity of clinical presentations and the difficulty in
making the diagnosis of acute appendicitis in pregnant women is well established. This is particularly true in the late second trimester
and the third trimester, when many abdominal symptoms may be considered pregnancy related. In addition, during pregnancy there are
anatomic changes in the appendix (Fig. 30-7) and increased abdominal laxity that may further complicate clinical evaluation. There is no
association between appendectomy and subsequent fertility.
Fig. 30-7.
Location of the appendix during pregnancy. ASIS = anterior superior iliac spine.
[Reproduced with permission from Metcalf A: The appendix, in Corson JD, Williamson RCN (eds): Surgery. London: Mosby, 2001.]
Appendicitis in pregnancy should be suspected when a pregnant woman complains of abdominal pain of new onset. The most consistent
sign encountered in acute appendicitis during pregnancy is pain in the right side of the abdomen. Seventy-four percent of patients report
pain located in the right lower abdominal quadrant, with no difference between early and late pregnancy. Only 57% of patients present
with the classic history of diffuse periumbilical pain migrating to the right lower quadrant. Laboratory evaluation is not helpful in
establishing the diagnosis of acute appendicitis during pregnancy. The physiologic leukocytosis of pregnancy has been defined as high as
16,000 cells/mm3. In one series only 38% of patients with appendicitis had a white blood cell count of >16,000 cells/mm3.68 Recent data
suggest that the incidence of perforated or complex appendicitis is not increased in pregnant patients. 69
When the diagnosis is in doubt, abdominal ultrasound may be beneficial. Another option is magnetic resonance imaging, which has no
known deleterious effects on the fetus. The American College of Radiology recommends the use of nonionizing radiation techniques for
front-line imaging in pregnant women.70 Laparoscopy has been advocated in equivocal cases, especially early in pregnancy; however
laparoscopic appendectomy may be associated with an increase in pregnancy-related complications. In an analysis of outcomes in
California using administrative databases, laparoscopy was found to be associated with a 2.31 increased odds of fetal loss over open
surgery.69
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 a negative appendectomy and with simple appendicitis. It is important to
note that a negative appendectomy is not a benign procedure. Removing a normal appendix is associated with a 4% risk of fetal loss and
10% risk of early delivery. Maternal mortality after appendectomy is extremely rare (0.03%). Because the incidence of ruptured
appendix is similar in pregnant and nonpregnant women and because maternal mortality is so low, it appears that the greatest
opportunity to improve fetal outcomes is by improving diagnostic accuracy and reducing the rate of negative appendectomy.68–71
Appendicitis in Patients with AIDS or HIV Infection
The incidence of acute appendicitis in HIV-infected patients is reported to be 0.5%. This is higher than the 0.1 to 0.2% incidence
reported for the general population.72 The presentation of acute appendicitis in HIV-infected patients is similar to that in noninfected
patients. The majority of HIV-infected patients with appendicitis have fever, periumbilical pain radiating to the right lower quadrant
(91%), right lower quadrant tenderness (91%), and rebound tenderness (74%). HIV-infected patients do not manifest an absolute
leukocytosis; however, if a baseline leukocyte count is available, nearly all HIV-infected patients with appendicitis demonstrate a relative
leukocytosis.72,73
The risk of appendiceal rupture appears to be increased in HIV-infected patients. In one large series of HIV-infected patients who
underwent appendectomy for presumed appendicitis, 43% of patients were found to have perforated appendicitis at laparotomy.74 The
increased risk of appendiceal rupture may be related to the delay in presentation seen in this patient population. 72,74 The mean duration
of symptoms before arrival in the emergency department has been reported to be increased in HIV-infected patients, with >60% of
patients reporting the duration of symptoms to be longer than 24 hours.72 In early series, significant hospital delay also may have
contributed to high rates of rupture.72 However, with increased understanding of abdominal pain in HIV-infected patients, hospital delay
has become less prevalent.72,75 A low CD4 count is also associated with an increased incidence of appendiceal rupture. In one large
series, patients with nonruptured appendices had CD4 counts of 158.75 ± 47 cells/mm3 compared with 94.5 ± 32 cells/mm3 in patients
with appendiceal rupture.72
The differential diagnosis of right lower quadrant pain is expanded in HIV-infected patients compared with the general population. In
addition to the conditions discussed elsewhere in this chapter, opportunistic infections should be considered as a possible cause of right
lower quadrant pain.72–75 Such opportunistic infections include cytomegalovirus (CMV) infection, Kaposi's sarcoma, tuberculosis,
lymphoma, and other causes of infectious colitis. CMV infection may be seen anywhere in the GI tract. CMV infection causes a vasculitis
of blood vessels in the submucosa of the gut, which leads to thrombosis. Mucosal ischemia develops, leading to ulceration, gangrene of
the bowel wall, and perforation. Spontaneous peritonitis may be caused by opportunistic pathogens, including CMV, Mycobacterium
avium-intracellulare complex, Mycobacterium tuberculosis, Cryptococcus neoformans, and Strongyloides. Kaposi's sarcoma and nonHodgkin's lymphoma may present with pain and a right lower quadrant mass. Viral and bacterial colitis occur with a higher frequency in
HIV-infected patients than in the general population. Colitis should always be considered in HIV-infected patients presenting with right
lower quadrant pain. Neutropenic enterocolitis (typhlitis) should also be considered in the differential diagnosis of right lower quadrant
pain in HIV-infected patients.73,75
A thorough history and physical examination is important when evaluating any patient with right lower quadrant pain. In the HIVinfected patient with classic signs and symptoms of appendicitis, immediate appendectomy is indicated. In those patients with diarrhea
as a prominent symptom, colonoscopy may be warranted. In patients with equivocal findings, CT scan is usually helpful. The majority of
pathologic findings identified in HIV-infected patients who undergo appendectomy for presumed appendicitis are typical. The negative
appendectomy rate is 5 to 10%. However, in up to 25% of patients AIDS-related entities are found in the operative specimens, including
CMV, Kaposi's sarcoma, and M. avium-intracellulare complex.72,74
In a retrospective study of 77 HIV-infected patients from 1988 to 1995, the 30-day mortality rate for patients undergoing appendectomy
was reported to be 9.1%.72 More recent series report 0% mortality in this group of patients.75 Morbidity rates for HIV-infected patients
with nonperforated appendicitis are similar to those seen in the general population. Postoperative morbidity rates appear to be higher in
HIV-infected patients with perforated appendicitis. In addition, the length of hospital stay for HIV-infected patients undergoing
appendectomy is twice that for the general population.72,75 No series has been reported to date that addresses the role of laparoscopic
appendectomy in the HIV-infected population.
Treatment
Despite the advent of more sophisticated diagnostic modalities, the importance of early operative intervention should not be minimized.
Once the decision to operate for presumed acute appendicitis has been made, the patient should be prepared for the operating room.
Adequate hydration should be ensured, electrolyte abnormalities should be corrected, and pre-existing cardiac, pulmonary, and renal
conditions should be addressed. A large meta-analysis has demonstrated the efficacy of preoperative antibiotics in lowering the
infectious complications in appendicitis.23 Most surgeons routinely administer antibiotics to all patients with suspected appendicitis. If
simple acute appendicitis is encountered, there is no benefit in extending antibiotic coverage beyond 24 hours. If perforated or
gangrenous appendicitis is found, antibiotics are continued until the patient is afebrile and has a normal white blood cell count. For intraabdominal infections of GI tract origin that are of mild to moderate severity, the Surgical Infection Society has recommended singleagent therapy with cefoxitin, cefotetan, or ticarcillin-clavulanic acid. For more severe infections, single-agent therapy with carbapenems
or combination therapy with a third-generation cephalosporin, monobactam, or aminoglycoside plus anaerobic coverage with clindamycin
or metronidazole is indicated.24 The recommendations are similar for children.76
OPEN APPENDECTOMY
For open appendectomy most surgeons use either a McBurney (oblique) or Rocky-Davis (transverse) right lower quadrant musclesplitting incision in patients with suspected appendicitis. The incision should be centered over either the point of maximal tenderness or a
palpable mass. If an abscess is suspected, a laterally placed incision is imperative to allow retroperitoneal drainage and to avoid
generalized contamination of the peritoneal cavity. If the diagnosis is in doubt, a lower midline incision is recommended to allow a more
extensive examination of the peritoneal cavity. This is especially relevant in older patients with possible malignancy or diverticulitis.
Several techniques can be used to locate the appendix. Because the cecum usually is visible within the incision, the convergence of the
taeniae can be followed to the base of the appendix. A sweeping lateral to medial motion can aid in delivering the appendiceal tip into
the operative field. Occasionally, limited mobilization of the cecum is needed to aid in adequate visualization. Once identified, the
appendix is mobilized by dividing the mesoappendix, with care taken to ligate the appendiceal artery securely.
The appendiceal stump can be managed by simple ligation or by ligation and inversion with either a purse-string or Z stitch. As long as
the stump is clearly viable and the base of the cecum is not involved with the inflammatory process, the stump can be safely ligated with
a nonabsorbable suture. The mucosa is frequently obliterated to avoid the development of mucocele. The peritoneal cavity is irrigated
and the wound closed in layers. If perforation or gangrene is found in adults, the skin and subcutaneous tissue should be left open and
allowed to heal by secondary intent or closed in 4 to 5 days as a delayed primary closure. In children, who generally have little
subcutaneous fat, primary wound closure has not led to an increased incidence of wound infection.
If appendicitis is not found, a methodical search must be made for an alternative diagnosis. The cecum and mesentery should first be
inspected. Next, the small bowel should be examined in a retrograde fashion beginning at the ileocecal valve and extending at least 2 ft.
In females, special attention should be paid to the pelvic organs. An attempt also should be made to examine the upper abdominal
contents. Peritoneal fluid should be sent for Gram's staining and culture. If purulent fluid is encountered, it is imperative that the source
be identified. A medial extension of the incision (Fowler-Weir), with division of the anterior and posterior rectus sheath, is acceptable if
further evaluation of the lower abdomen is indicated. If upper abdominal pathology is encountered, the right lower quadrant incision is
closed and an appropriate upper midline incision is made.9
LAPAROSCOPIC APPENDECTOMY
Semm first reported successful laparoscopic appendectomy several years before the first laparoscopic cholecystectomy. 10 However, the
laparoscopic approach to appendectomy did not come into widespread use until after the success of laparoscopic cholecystectomy. This
may be due to the fact that appendectomy, by virtue of its small incision, is already a form of minimal-access surgery.77
Laparoscopic appendectomy is performed under general anesthesia. A nasogastric tube and a urinary catheter are placed before
obtaining a pneumoperitoneum. Laparoscopic appendectomy usually requires the use of three ports. Four ports may occasionally be
necessary to mobilize a retrocecal appendix. The surgeon usually stands to the patient's left. One assistant is required to operate the
camera. One trocar is placed in the umbilicus (10 mm), and a second trocar is placed in the suprapubic position. Some surgeons place
this second port in the left lower quadrant. The suprapubic trocar is either 10 or 12 mm, depending on whether or not a linear stapler
will be used. The placement of the third trocar (5 mm) is variable and usually is either in the left lower quadrant, epigastrium, or right
upper quadrant. Placement is based on location of the appendix and surgeon preference. Initially, the abdomen is thoroughly explored to
exclude other pathology. The appendix is identified by following the anterior taeniae to its base. Dissection at the base of the appendix
enables the surgeon to create a window between the mesentery and the base of the appendix (Fig. 30-8A). The mesentery and base of
the appendix are then secured and divided separately. When the mesoappendix is involved with the inflammatory process, it is often
best to divide the appendix first with a linear stapler and then to divide the mesoappendix immediately adjacent to the appendix with
clips, electrocautery, Harmonic Scalpel, or staples (Fig. 30-8B and 30-8C). The base of the appendix is not inverted. The appendix is
removed from the abdominal cavity through a trocar site or within a retrieval bag. The base of the appendix and the mesoappendix
should be evaluated for hemostasis. The right lower quadrant should be irrigated. Trocars are removed under direct vision.78,79
Fig. 30-8.