The Appendix

ANATOMY AND FUNCTION

The appendix first becomes visible during embryologic development in the eighth week of life 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, displacing the appendix 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. These anatomic considerations have

significant clinical importance in the context of acute appendicitis. The three taenia 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 less than 1 to greater than 30 cm; most appendices are 6 to 9 cm in length. Appendiceal absence, duplication, and

diverticula have all been described.

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 which

actively participates in the secretion of immunoglobulins, particularly IgA. Though the appendix is an integral component of the gut-associated lymphoid tissue (GALT) system, its

function is not essential and appendectomy has not been associated with any predisposition to sepsis or any other manifestation of immune compromise. Lymphoid tissue first

appears in the appendix about 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, virtually no lymphoid tissue remains within the appendix and complete obliteration of the appendiceal lumen is common.

INFLAMMATION OF THE APPENDIX
Acute Appendicitis

Historical Background

There is evidence in the literature that alchemists and physicians in the 1500s recognized the existence of a clinical entity associated with severe inflammation of the cecal region,

known as “perityphlitis.” Although the first successful appendectomy was reported in 1736, it was not until 1886 that Reginald Fitz helped establish the role of surgical removal of

the inflamed appendix as curative therapy for this disease, which was once thought to be fatal. In 1889, Charles McBurney presented his classic report before the New York

Surgical Society on the importance of early operative intervention for acute appendicitis in which he described the point of maximal abdominal tenderness to be determined by the

pressure of one finger placed one-third of the distance between the anterior superior iliac spine and the umbilicus. Five years later he devised the muscle-splitting incision which

today bears his name.

Incidence

Appendicitis remains one of the most common acute surgical diseases. The incidence of acute appendicitis roughly parallels that of lymphoid development, with the peak incidence

in early adulthood. Appendicitis occurs more frequently in males especially at the time of puberty. A review of over 2000 patients with appendicitis demonstrated an overall 1.3:1

male predominance.

A decline from 100 cases per 100,000 population to 52 cases per 100,000 population was demonstrated over a study period from 1975 to 1991. This degree of change does not

seem to be explained by improved diagnosis, and the explanation for this phenomenon remains elusive. Currently, 84 percent of all appendectomies are performed for acute

pathology. The rate of normal appendectomy averages 16 percent, with females comprising 68 percent of those patients found to have a normal appendix at exploration.

Etiology and Pathogenesis

Obstruction of the lumen is the dominant causal factor in acute appendicitis. Fecaliths are the usual cause of appendiceal obstruction. Less common are hypertrophy of lymphoid

tissue; inspissated barium from previous x-ray studies; vegetable and fruit seeds; and intestinal worms, particularly ascarids.

The frequency of obstruction rises with the severity of the inflammatory process. Fecaliths are found in about 40 percent of cases of simple acute appendicitis, about 65 percent of

cases of gangrenous appendicitis without rupture, and about 90 percent of cases of gangrenous appendicitis with rupture.

The probable sequence of events following occlusion of the lumen is as follows. A closed-loop obstruction is produced by the proximal block, and continuing normal secretion of the

appendiceal mucosa rapidly produces distention. The luminal capacity of the normal appendix is only about 0.1 mL—there is no real lumen. Secretion of as little as 0.5 mL distal to

a block raises the intraluminal pressure to about 60 cmH 2O. The human being is one of the few animals with an appendix capable of secreting at pressures high enough to lead to

gangrene and perforation. Distention stimulates nerve endings of visceral afferent pain fibers, producing vague, dull, diffuse pain in the midabdomen or lower epigastrium.

Peristalsis is also stimulated by the rather sudden distention, so that some cramping may be superimposed on the visceral pain early in the course of appendicitis.

Distention continues, not only from continued mucosal secretion, but also from rapid multiplication of the resident bacteria of the appendix. 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. Distension of this magnitude

usually causes reflex nausea and vomiting, and the diffuse visceral pain becomes more severe. The inflammatory process soon involves the serosa of the appendix and in turn

parietal peritoneum in the region, producing the characteristic shift in pain to the right lower quadrant.

The mucosa of the gastrointestinal tract, including the appendix, is very susceptible to impairment of blood supply. Thus its integrity is compromised early in the process, allowing

bacterial invasion of the deeper coats. As progressive distention encroaches on the arteriolar pressure, 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.

This sequence is not inevitable; 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.

Bacteriology

A variety of anaerobes, aerobes, or facultative bacteria have been cultured from peritoneal fluid, abscess contents, and appendiceal tissue in patients with gangrenous or

perforated appendicitis. An average of 10 different organisms were recovered per specimen. Bacteroides fragilis and Escherichia coli were isolated from almost all specimens.

Other frequent isolates were Peptostreptococcus (80 percent), Pseudomonas (40 percent), Bacteroides splanchnicus (40 percent), and Lactobacillus (37 percent).

A quantitative bacteriologic study of the appendix wall of children showed no significant differences between the flora of normal and of acutely inflamed appendices. Bacteroides, E.

coli, and streptococci were the most common organisms isolated.

Cytomegalovirus-associated appendicitis has been reported in a patient with acquired immunodeficiency syndrome.

Clinical Manifestations

Symptoms

Abdominal pain is the prime symptom of acute appendicitis. Classically the 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 1to 12 h, but usually within 4 to 6 h, the pain localizes in the right lower quadrant. This

classic pain sequence, though 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 rectrocecal appendix may cause principally flank or back pain; a pelvic appendix, principally suprapubic pain; and a retroileal appendix may

cause testicular pain, presumably from irritation of the spermatic artery and ureter. Malrotation is also 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. Vomiting occurs in about 75 percent of

patients, but is not prominent or prolonged, and most patients vomit only once or twice.

Most patients give a history of obstipation from before the onset of abdominal pain, and many feel that defecation would relieve their abdominal pain. However, diarrhea occurs in

some patients, particularly children, so that the pattern of bowel function is of little differential diagnostic value.

The sequence of symptom appearance has great differential diagnostic significance. In over 95 percent 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 should be questioned.

Signs

Physical findings are determined principally by the anatomic position of the inflamed appendix as well as by whether the organ has already ruptured when the patient is first

examined.

Vital signs are not changed very much by uncomplicated appendicitis. Temperature elevation is rarely more than 1°C; the pulse rate is normal or slightly elevated. Changes of

greater magnitude usually mean that a complication has occurred or that another diagnosis should be considered.

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 gingerly.

The classic right lower quadrant physical signs are present when the inflamed appendix lies in the anterior position. Tenderness is often maximal at or near the point described by

McBurney as being “located exactly between an inch and a half and two inches from the anterior spinous process of the ileum on a straight line drawn from that process to the

umbilicus.” Direct rebound tenderness is usually present, and referred or indirect rebound tenderness is frequently present, and the tenderness is felt maximally in the right lower

quadrant, indicating peritoneal irritation. Rovsing's 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 but not always accompanies acute appendicitis.

In patients with obvious appendicitis, this sign is superfluous, but in some early cases it may be the first positive sign. It is elicited either by needle prick or, better, by gently picking

up the skin between the forefinger and thumb. This ordinarily is not unpleasant but is painful in areas of cutaneous hyperesthesia.

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—true reflex rigidity as opposed to voluntary guarding.

Variations in the position of the inflamed appendix produce variations from the usual in 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 the cul-de-sac of Douglas, pain is felt in the suprapubic area as well as locally.

Signs of localized muscle irritation may also be present. The psoas sign indicates an irritative focus in proximity to that muscle. The test is performed by having patients lie on their

left side; the examiner then slowly extends the right thigh, thus stretching the iliopsoas muscle. The test is positive if extension produces pain. Similarly, a positive obturator sign of

hypogastric pain on stretching the obturator internus indicates irritation at that locus. 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/mm 3, is usually present in patients with acute, uncomplicated appendicitis and is often accompanied by a moderate

polymorphonuclear predominance. If a normal white blood cell count with no left shift is present, the diagnosis of acute appendicitis should be reconsidered. It is unusual for the

white blood cell count to be greater than 18,000/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 catheterized urine specimen will not be seen with acute appendicitis.

Plain films of the abdomen, although frequently obtained as part of the general evaluation of a patient with an acute abdomen, are rarely helpful in diagnosing acute appendicitis,

although they can be of significant benefit in ruling out additional 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 when present is highly suggestive of the diagnosis. A chest x-ray is sometimes indicated to rule out

referred pain from a right lower lobe pneumonic process.

Graded compression sonography has been suggested as an accurate way to establish the diagnosis of appendicitis. 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. A scan is considered positive if a

noncompressible appendix 6 mm or greater in the anteroposterior direction is demonstrated (Fig. 27-1). The presence of an appendicolith establishes the diagnosis. Sonographic

demonstration of a normal appendix, which is an easily compressible blind-ending tubular structure measuring 5 mm or less, excludes the diagnosis of acute appendicitis. The study

is considered negative 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 transabdominally or by endovaginal examination in order to exclude gynecologic pathology as a possible cause of acute abdominal pain. The sonographic diagnosis of acute

appendicitis has a reported sensitivity of 78 to 96 percent and a specificity of 85 to 98 percent. Sonography is similarly effective in children and pregnant women, although its

application is somewhat limited in late pregnancy.

Sonography has definite limitations and results are user-dependent. A false-positive scan 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 not because

of an acutely inflamed appendix but because of overlying fat. False-negative sonograms can occur if appendicitis is confined to the appendiceal tip, the cecum is retrocecal in

location, the appendix is markedly enlarged and mistaken for small bowel, or if the appendix is perforated and therefore compressible.

Additional radiographic techniques include computed tomography, barium enema, and radioisotope-labeled leukocyte scans. Although CT has been reported to be as, or more,

accurate than sonography, it is significantly more expensive. Because of the cost and added radiation exposure, CT should be used primarily when an appendiceal abscess is

suspected to ascertain the feasibility of percutaneous drainage. Diagnosis based on barium enema depends on the nonspecific findings of extrinsic mass effect on the cecum and

nonfilling of the appendix, and is associated with an accuracy ranging from 50 to 84 percent. Radiographic evaluation of patients with suspected appendicitis should be reserved for

patients in whom the diagnosis is in doubt and should not delay, or substitute for, prompt operative intervention when clinically indicated.

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 for the evaluation of females with lower abdominal complaints, since appendectomy is performed on a normal appendix in as many as 30 to 40 percent of such patients.

Differentiating acute gynecologic pathology from acute appendicitis is easily accomplished using the laparoscope.

Appendiceal Rupture

Immediate appendectomy has long been the recommended treatment of acute appendicitis because of the known progression to rupture. A study on the natural history of

appendicitis demonstrated a rate of 14 percent normal, 70 percent inflamed, and 16 percent perforated appendices. This study suggested that delays in presentation were

responsible for the majority of perforated appendices. There is no accurate way of determining when and if an appendix will rupture prior to resolution of the inflammatory process.

Although it has been suggested that observation and antibiotic therapy alone may be an appropriate treatment for acute appendicitis, nonoperative treatment risks the morbidity and

mortality associated with a ruptured appendix.

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 greater than 39°C (102°F) and a white blood cell count greater than 18,000/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 percent of cases, an ill-defined mass will be detected on physical examination. This could represent a phlegmon, which is matted loops of bowel adherent to the adjacent

inflamed appendix, or a periappendiceal abscess. Patients who present with a mass have a longer duration of symptoms, usually at least 5 to 7 days. The ability to distinguish

acute, uncomplicated appendicitis from perforation on the basis of clinical findings is often difficult, but it is important to make the distinction since their treatment differs. CT scan

may be very beneficial in guiding therapy. Phlegmons and small abscesses can be treated conservatively with intravenous antibiotics; well-localized abscesses may be managed

with percutaneous drainage; and 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 following the acute event has

classically been recommended for all patients treated either nonoperatively or with simple drainage of an abscess. The reported incidence of recurrent appendicitis in patients not

undergoing interval appendectomy ranges from 0 to 37 percent, and is highest during the first year. Because a perforated cecal carcinoma can be mistaken for an appendiceal

abscess, all patients over the age of 50 years should undergo either barium enema or colonoscopic examination prior to interval appendectomy.

Differential Diagnosis

The differential diagnosis of acute appendicitis is essentially the diagnosis of the “acute abdomen” . This is because clinical manifestations are not specific for a given

disease but are specific for disturbance of a physiologic function or functions. Thus an essentially identical clinical picture can result from a wide variety of acute processes within or

near the peritoneal cavity that produce the same alterations of function as acute appendicitis.

Accuracy of preoperative diagnosis should be about 85 percent. If it is consistently less, some unnecessary operations are probably being done, and a more rigorous preoperative

differential diagnosis is in order. On the other hand, an accuracy consistently greater than 90 percent should also cause concern, since this may mean that some patients with

atypical but bona fide acute appendicitis are being “observed” when they should have prompt surgical intervention. The Haller group has shown, however, that this is not invariably

true. Before their study, the perforation rate at the hospital where the study took place was 26.7 percent, and acute appendicitis was found at 80 percent of the operations. By a

policy of intensive in-hospital observation when the diagnosis of appendicitis was unclear, the group raised the rate of acute appendicitis found at operation to 94 percent, while the

perforation rate remained unchanged at 27.5 percent.

There are a few conditions in which operation is contraindicated, but in general the disease processes that are confused with appendicitis are also surgical problems or, if not, are

not made worse by surgical intervention. The more frequent 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—accounting

for more than 75 percent—in descending order of frequency are acute mesenteric lymphadenitis, no organic pathologic condition, acute pelvic inflammatory disease, twisted ovarian

cyst or ruptured graafian follicle, and acute gastroenteritis.

Differential diagnosis of appendicitis depends upon three major factors: the anatomic location of the inflamed appendix; the stage of the process, that is, whether simple or

ruptured; and the age and sex of the patient.

Acute Mesenteric Adenitis

This is the disease most often confused with acute appendicitis in children. Almost invariably an upper respiratory infection is present or has recently subsided. The pain is usually

less or more 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, since mesenteric adenitis is a self-limited disease, but if the differentiation remains in

doubt, immediate operation is the only safe course.

Acute Gastroenteritis

This is very common in childhood but can usually be easily differentiated from appendicitis. Viral gastroenteritis, an acute self-limited infection of diverse causes, is characterized by

profuse watery 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 are normal.

Salmonella gastroenteritis results from ingestion of contaminated food. Abdominal findings are usually similar to those in viral gastroenteritis, but in some cases the abdominal pain

is intense, localized, and associated with rebound tenderness. Chills and fever are common. The leukocyte count is usually normal. The causative organisms can be isolated from

essentially 100 percent of patients, but culturing may take too long to help the clinician in making a timely differential diagnosis in cases of abdominal pain. Similar attacks in other

persons eating the same food as the patient greatly strengthen the presumptive diagnosis of salmonella gastroenteritis.

Typhoid fever is now a rare disease. This probably accounts for the frequency of missed diagnosis—it is rarely seen and rarely thought of. The onset is less acute than in

appendicitis, with a prodrome of several days. Differentiation is usually possible because of the prostration, maculopapular rash, inappropriate bradycardia, and leukopenia.

Diagnosis is confirmed by culture of Salmonella typhosa from stool or blood. Intestinal perforation, usually in the lower ileum, develops in about 1 percent of cases and requires

immediate surgical therapy.

Diseases of the Male

Diseases of males must be considered in differential diagnosis of appendicitis, including torsion of the testis and acute epididymitis, since epigastric pain may overshadow local

symptoms early in these diseases. Seminal vesiculitis may also mimic appendicitis but can be diagnosed by palpating the enlarged, tender seminal vesicle on rectal examination.

Meckel's Diverticulitis

This causes a clinical picture very similar to that of acute appendicitis. Preoperative differentiation is academic and unnecessary, since Meckel's diverticulitis is associated with the

same complications as appendicitis and requires the same treatment—prompt surgical intervention. Diverticulectomy can nearly always be done through a McBurney incision,

extended if necessary. If the base of the diverticulum is broad, so that removal would compromise the lumen of the ileum, then resection of the segment of ileum bearing the

diverticulum with end-to-end anastomosis is done.

Intussusception

In contrast to Meckel's diverticulitis, it is extremely important to differentiate intussusception from acute appendicitis, because the treatment is quite different. The age of the patients

is important: appendicitis is very uncommon under age 2, whereas nearly all idiopathic intussusceptions occur under age 2. Intussusception occurs typically in a well-nourished

infant who is suddenly doubled up by apparent colicky pain. Between attacks of pain the infant appears quite well. After several hours, the patient usually passes a bloody mucoid

stool. A sausage-shaped mass may be palpable in the right lower quadrant. Later, as the intussusception progresses distad, the right lower quadrant feels abnormally empty. The

preferred treatment of intussusception, if seen before signs of peritonitis supervene, is reduction by barium enema, but treatment of acute appendicitis by barium enema may be

catastrophic.

Regional Enteritis

The manifestations of acute regional enteritis—fever, right lower quadrant pain and tenderness, and leukocytosis—often simulate acute appendicitis. Diarrhea and the infrequency

of anorexia, nausea, and vomiting favor a diagnosis of enteritis but are not sufficient to exclude acute appendicitis without celiotomy. In an appreciable percentage of patients with

chronic regional enteritis, the diagnosis has been first made at the time of operation for presumed acute appendicitis. Acute ileitis should be distinguished from Crohn's disease. In

the face of an acutely inflamed distal ileum with no cecal involvement and a normal appendix, appendectomy is indicated. Progression to Crohn's ileitis is uncommon.

Perforated Peptic Ulcer

Perforated peptic ulcer closely simulates appendicitis if the spilled gastroduodenal contents gravitate down the right gutter to the cecal area and if the perforation spontaneously

seals fairly soon, thus minimizing upper abdominal findings.

Other Lesions

Diverticulitis or perforating carcinoma of the cecum or of that portion of the sigmoid that lies on the right side may be impossible to distinguish from appendicitis. Extensive

diagnostic studies in an attempt to make a preoperative differentiation are not warranted.

Epiploic Appendagitis

Epiploic appendagitis probably results from infarction of the 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 is commonly unaffected. Localized tenderness over the site is usual and is often marked on rebound but without rigidity. In 25 percent of

reported cases, pain has persisted or recurred until the infarcted epiploic appendages were removed.

Urinary Tract Infection

Acute pyelonephritis, on the right side particularly, may mimic a retroileal acute appendicitis. Chills, right costovertebral angle tenderness, pus cells, and particularly bacteria in the

urine usually suffice to differentiate the two.

Ureteral Stone

If the calculus is lodged near the appendix, it may simulate a retrocecal appendicitis. Pain referred to the labia, scrotum, or penis; hematuria; and/or absence of fever or leukocytosis

suggest stone. Pyelography usually confirms the diagnosis.

Primary Peritonitis

Primary peritonitis rarely mimics simple acute appendicitis but presents a picture very similar to diffuse peritonitis secondary to a ruptured appendix. The diagnosis is made by

peritoneal aspiration. If nothing but cocci are seen on the Gram's-stained smear, peritonitis is primary and treated medically; if the flora are mixed, secondary peritonitis is indicated.

Henoch-Schönlein Purpura

This syndrome usually occurs 2 to 3 weeks after a streptococcal infection. Abdominal pain may be prominent, but joint pains, purpura, and nephritis are nearly always present also.

Yersiniosis

Human infection with Yersinia enterocolitica or Y. pseudotuberculosis is probably transmitted through food contaminated by feces or urine. Yersinia infections cause a variety of

clinical syndromes, including mesenteric adenitis, ileitis, colitis, and acute appendicitis. Many of the infections are mild and self-limited, but some lead to a systemic septic course

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, since appendicitis caused by Yersinia cannot be clinically distinguished from appendicitis of other causation. About 6 percent of cases of

mesenteric adenitis and 5 percent of cases of acute appendicitis are caused by Yersinia infection.

Campylobacter jejuni causes diarrhea and pain that mimics the pain of appendicitis. The organism can be cultured from stool.

Gynecologic Disorders

The rate of erroneous diagnosis of acute appendicitis is highest in young adult females. Rates of appendectomy being performed on a normal appendix of 32 to 45 percent have

been reported in women 15 to 45 years old. Diseases of the female internal generative organs that may be erroneously 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. Laparoscopy plays a

significant role in establishing the diagnosis.

Pelvic Inflammatory Disease

The infection is usually bilateral but if confined to the right tube may mimic acute appendicitis. Nausea and vomiting are nearly always present in patients with appendicitis, but only

in approximately half of those with pelvic inflammatory disease. The greatest value of these symptoms for establishing a diagnosis of pelvic inflammatory disease is their absence.

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 appendicitis to pelvic inflammatory disease is low in the early phase of the menstrual cycle and high during the luteal phase. The clinical use of all the above-mentioned

distinctions has resulted in a reduction of the incidence of negative findings on laparotomy in young women to 15 percent.

Ruptured Graafian Follicle

Not uncommonly, ovulation results in the spill of sufficient blood and follicular fluid to produce brief, mild lower abdominal pain. If the fluid is unusually copious and from the right

ovary, appendicitis may be simulated. Pain and tenderness are rather diffuse. Leukocytosis and fever are minimal or absent. Since this pain occurs at the midpoint of the menstrual

cycle, it is often called mittelschmerz.

Other Diseases

Diseases not mentioned in the previous sections that occur in patients of all ages and both sexes and that must be considered in the differential diagnosis of appendicitis are

foreign body perforations of the bowel; closed-loop intestinal obstruction; mesenteric vascular occlusion; pleuritis of the right lower chest; acute cholecystitis; acute pancreatitis;

hematoma of the abdominal wall; and numerous conditions too rare to mention.

Appendicitis in the Young

The establishment of a diagnosis of acute appendicitis in the young is even more difficult 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 gastrointestinal upset in children are all contributing factors. 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. In a study of 1366 specimens from pediatric patients undergoing

appendectomies, histologic analysis revealed 12 percent normal appendices, 68 percent nonperforated appendices, and 20 percent perforated appendices. Children under 8 years

old had a twofold increase in the rate of perforation as compared to older children. The incidence of major complications was related to rupture, with an incidence of 1.2 percent in

simple appendicitis compared to 6.4 percent in perforated appendicitis. The treatment regimen for perforated appendicitis generally includes immediate appendectomy, antibiotic

irrigation of the peritoneal cavity, transperitoneal drainage through the wound, and a 10-day antibiotic treatment regimen. Laparoscopic appendectomy has also been shown to be

safe and effective in children.

Appendicitis in the Elderly

Although the incidence of appendicitis in the elderly is lower than in younger patients, the morbidity and mortality are significantly increased in this patient population. Delays in

diagnosis, a more rapid progression to perforation, and concomitant disease are all contributing factors. The diagnosis of appendicitis may be more subtle and less typical than in

younger individuals, and a high index of suspicion needs to be maintained. In patients over 80 years old, perforation rates of 49 percent and mortality rates of 21 percent have been

cited.

Appendicitis During Pregnancy

Appendicitis is the most frequently encountered extrauterine disease requiring surgical treatment during pregnancy. The incidence is approximately 1 in 2000 pregnancies. Acute

appendicitis can occur at any time during pregnancy but is more frequent during the first two trimesters. As fetal gestation progresses, the diagnosis of appendicitis becomes more

difficult as the appendix is displaced laterally and superiorly (Fig. 27-2). Nausea and vomiting after the first trimester or new-onset nausea and vomiting should raise the

consideration of appendicitis. Abdominal pain and tenderness will be present, although rebound and guarding are less frequent due to laxity of the abdominal wall. Elevation of the

white blood cell count above the normal pregnancy levels of 15,000 to 20,000/mm 3 with a predominance of polymorphonuclear cells is usually present. When the diagnosis is in

doubt, abdominal ultrasound may be beneficial. Laparoscopy may be indicated in equivocal cases, especially early in pregnancy. The performance of any operation during

pregnancy carries a risk of premature labor of 10 to 15 percent, and the risk is similar for both negative laparotomy and appendectomy for simple appendicitis. The most significant

factor associated with both fetal and maternal death is appendiceal perforation. Fetal mortality increases from 3 to 5 percent with early appendicitis to 20 percent with perforation.

The suspicion of appendicitis during pregnancy should prompt rapid diagnosis and surgical intervention.

Appendicitis in Patients with AIDS or HIV Infection

The cause of appendicitis in HIV-positive patients and patients with AIDS is similar to the cause of appendicitis in the general population. In some cases, however, an underlying

opportunistic infection, usually secondary to cytomegalovirus or Kaposi's sarcoma, may be responsible for the development of appendiceal inflammation. Although the clinical

presentation of appendicitis in patients who have AIDS or are HIV-positive does not differ significantly from patients without AIDS or HIV infection, the leukocytosis usually noted in

acute appendicitis may not be present. Cytomegalovirus enteritis and tuberculosis or lymphoma involving the distal ileum can mimic appendicitis. Diagnostic laparoscopy can be

helpful, with laparoscopic appendectomy being indicated when an inflamed appendix is found. If appendectomy is performed prior to perforation, there is no increase in morbidity or

mortality.

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 insured, electrolyte abnormalities corrected, and

preexisting cardiac, pulmonary, and renal conditions should be addressed. Many trials have demonstrated the efficacy of preoperative antibiotics in lowering the infectious

complications in appendicitis. It is common practice by most surgeons to 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 h. 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 gastrointestinal tract origin of mild to moderate severity, the Surgical Infection Society has recommended

single-agent therapy with cefoxitin, cefotetan, or ticarcillin-clavulanic acid. For more severe infections, single-agent therapy with carbapenems or combination therapy with a thirdgeneration

cephalosporin, monobactam, or aminoglycoside, plus anaerobic coverage with clindamycin and metronidazole, is indicated.

Open Appendectomy 

Most surgeons employ either a McBurney (oblique) or Rocky-Davis (transverse) right lower quadrant muscle-splitting incision in patients with suspected appendicitis. The incision

should be centered over the point of maximal tenderness or a palpable mass. If an abscess is suspected, a laterally placed incision is imperative to avoid generalized contamination

of the peritoneal cavity. If the diagnosis is in doubt, a lower midline incision is recommended by some to allow a more extensive examination of the peritoneal cavity.

Several techniques can be used to locate the appendix. Since the cecum is usually visible within the incision, the convergence of the taeniae can be followed to the base of the

appendix. A sweeping laterial 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, taking care 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 tradition dictates. As long as the stump is clearly viable and the base of the cecum

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 a

mucocele. The peritoneal cavity is irrigated and the wound closed in layers. If perforation or gangrene is found, the skin and subcutaneous tissue should be left open and allowed to

heal by secondary intent or be 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 for an alternative diagnosis must be performed. The cecum and mesentery should first be inspected. Next, the small bowel is

examined in a retrograde fashion beginning at the ileocecal valve. In females, special attention should be paid to the pelvic organs. An attempt is also made to examine the upper

abdominal contents. Peritoneal fluid should be sent for Gram's stain 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 performed.

Laparoscopy

Laparoscopy has emerged as a new technique for both the diagnosis and treatment of acute appendicitis. Laparoscopy can be of enormous assistance in the evaluation of young

women of childbearing age in whom acute appendicitis is suspected. Laparoscopic appendectomy may be preferable in obese patients who would require a large incision for the

open approach or in individuals who are particularly concerned about cosmesis. There are a number of theoretical advantages for the laparoscopic approach over the traditional

open operation described over 100 years ago. These include decreased incidence of wound infection, less pain for the patient, reduced hospitalization, and a more rapid return to

employment. The data have not demonstrated any significant economic benefit to laparoscopic appendectomy for the general population. Both operative time and supply costs are

increased while duration of hospital stay is not significantly shortened. Nonetheless, laparoscopic appendectomy has been demonstrated to be a safe and effective treatment.

Recently reported prospective randomized trials comparing open and laparoscopic techniques (Table 27-1) indicate that operative time is generally greater using the laparoscopic

approach, but the time between the operation and return to activity, and the rate of wound infection, are decreased.

The superiority of laparoscopic appendectomy over the conventional approach continues to be an issue of some debate. Laparoscopy's most important role is in diagnostic

evaluation of young females whose symptoms are not the classical symptoms of appendicitis and in patients in whom the diagnosis remains in question. It does provide

visualization the entire abdominal cavity, unlike the limited exposure provided by a right lower quadrant incision. For properly trained personnel, laparoscopic appendectomy may be

appropriate for most cases of appendicitis, with a conversion rate of approximately 10 percent, mostly in patients with ruptured appendices.

The principles behind laparoscopic appendectomies are similar to those for other laparoscopic procedures (Fig. 27-4). All patients should have an indwelling urinary catheter and

nasogastric tube inserted prior to trochar insertion. The surgeon frequently stands to the patient's left with the video monitor at the foot of the table, or to the patient's right.

Pneumoperitoneum is established and a 10-mm trochar cannula is inserted through the umbilicus. A 10-mm forward-viewing laparoscope is placed through the cannula and the

peritoneal cavity is inspected. Next, a 10-mm trochar is introduced into the suprapubic region in the midline and additional 5-mm ports placed in either the right upper or lower

quadrant. Exposure is facilitated by placing the patient in the Trendelenburg position, right side up. Generally the cecum is easily visualized and the appendix easily identified.

Gentle traction can be applied to the mesoappendix by retracting the tip of the appendix with an atraumatic grasper placed through the right upper quadrant trochar. The

mesoappendix is divided with a stapling device or by using electrocautery for dissection and clips or a ligating loop to secure the appendiceal artery. Division of the mesoappendix

should be done as close to the appendix as possible. After the base of the appendix is adequately exposed, two ligating loops are placed proximally and one distally over the base.

The appendix is divided with scissors or electrocauterization. Alternatively, the appendix could be divided using a stapling device. Invagination of the appendiceal stump is not

routinely performed. The appendix is removed via the suprapubic trocar site.

The role of laparoscopic appendectomy for removal of the normal appendix has not been well defined. As for an open procedure, an appendectomy should be considered in

patients explored for right lower quadrant pain with no identifiable pathology. Complication rates of 1 to 3 percent have been reported under these circumstances. If the appendix is

normal, the same thorough search for an alternative diagnosis should be performed as with an open procedure.

Prognosis

Mortality

The mortality from appendicitis in the United States has steadily decreased from a rate of 9.9 per 100,000 in 1939 to 0.2 per 100,000 in 1986. Among the factors responsible are

the significantly decreasing incidence of appendicitis; better diagnosis and treatment, attributable to the now- available antibiotics, intravenous fluids, blood, and plasma; and a

higher percentage of patients receiving definitive treatment before rupture.

Principal factors in mortality are (1) whether rupture occurs before surgical treatment and (2) the age of the patient. The overall mortality rate in unruptured acute appendicitis is a

little higher than the rate for a general anesthetic, which is 0.06 percent. The overall mortality rate in ruptured acute appendicitis is about 3 percent—a 30-fold increase. The

mortality rate of ruptured appendicitis in the elderly is about 15 percent—a fivefold increase from the overall rate.

Death is usually attributable to uncontrolled sepsis—peritonitis, intraabdominal abscesses, or gram-negative septicemia. Sepsis may impose metabolic demands of such magnitude

on the cardiovascular or respiratory systems that they cannot be met, in which case cardiac or respiratory insufficiency is the direct cause of death. Pulmonary embolism continues

to account for some deaths. Aspiration causing the patient to drown in his or her own vomitus is a significant cause of death in the older age group.

Morbidity

Morbidity rates parallel mortality rates, being precipitously increased by rupture of the appendix and to a lesser extent by old age. In one report, complications occurred in 3 percent

of patients with nonperforated appendicitis and in 47 percent of patients with perforations. Most of the serious early complications are septic and include abscess and wound

infection. Wound infection is common but is nearly always confined to the subcutaneous tissues and promptly responds to wound drainage, which is accomplished by reopening the

skin incision. Wound infection predisposes to wound dehiscence also. The type of incision is relevant; complete dehiscence rarely occurs in a McBurney incision. The efficacy of

systemic antibiotics in reducing the incidence of wound infections has not been agreed on. But a significant reduction in morbidity has been shown in patients receiving

metronidazole or the combination of systemic clindamycin and topical ampicillin.

The incidence of intraabdominal abscesses secondary to peritoneal contamination from gangrenous or perforated appendicitis has decreased markedly since the introduction of

potent antibiotics. The sites of predilection for abscesses are the appendiceal fossa, pouch of Douglas, subhepatic space, and between loops of intestine. The latter are usually

multiple. Transrectal drainage is preferred for an abscess that bulges into the rectum.

Fecal fistula is an annoying but not particularly dangerous complication of appendectomy that may be caused by sloughing of that portion of the cecum inside a constricting

purse-string suture, by the ligature's slipping off a tied but not inverted appendiceal stump, or by necrosis from an abscess encroaching on the cecum.

Intestinal obstruction, initially paralytic but sometimes progressing to mechanical obstruction, may occur with slowly resolving peritonitis with loculated abscesses and exuberant

adhesion formation.

Late complications are quite uncommon. Adhesive band intestinal obstruction after appendectomy does occur but much less frequently than after pelvic surgical therapy. The

incidence of inguinal hernia is three times greater in patients who have had an appendectomy. Incisional hernia is like wound dehiscence in that infection predisposes to it, it rarely

occurs in a McBurney incision, and it is not uncommon in a lower right paramedian incision.

TUMORS

Appendiceal malignancies are rare, occurring in 0.5 percent of all appendectomies. The tumors are usually discovered at the time of laparotomy either as an incidental finding or in

association with acute inflammation of the appendix. In a recent review of over 2000 appendectomy specimens, histologic confirmation of appendiceal neoplasms included

carcinoid (0.27 percent), adenocarcinoma (0.14 percent), malignant mucocele (0.005 percent), and lymphoma (0.005 percent).

Carcinoid

The finding of a firm, yellow, bulbar mass in the appendix should raise the suspicion of an appendiceal carcinoid. The appendix is the most common site of gastrointestinal carcinoid

followed by the small bowel and rectum. Carcinoid syndrome is rarely associated with appendiceal carcinoid unless widespread metastases are present, which occurs in 2.9 percent

of cases. Symptoms attributable directly to the carcinoid are rare, though the tumor can occasionally obstruct the appendiceal lumen much like a fecalith and result in acute

appendicitis.

The majority of carcinoids are located in the tip of the appendix. Malignant potential is related to size, with tumors less than 2 cm rarely resulting in extension outside of the

appendix. In one report, 78 percent of appendiceal carcinoids were less than 1 cm, 17 percent were 1 to 2 cm, and only 5 percent were greater than 2 cm. Treatment rarely requires

more than simple appendectomy. For tumors less than 2 cm with extension into the mesoappendix, and for all tumors greater than 2 cm, a right hemicolectomy should be

performed.

Adenocarcinoma

Primary adenocarcinoma of the appendix is a rare neoplasm of three major histologic subtypes: mucinous adenocarcinoma, colonic adenocarcinoma, and adenocarcinoid. The

most common mode of presentation for appendiceal carcinoma is that of acute appendicitis. Patients may also present with ascites or a palpable mass, or the neoplasm may be

discovered during an operative procedure for an unrelated cause. The recommended treatment for all patients with adenocarcinoma of the appendix is a formal right

hemicolectomy. Appendiceal adenocarcinomas have a propensity for early perforation, though not clearly associated with a worsened prognosis. The presence of pseudomyxoma

peritonei secondary to mucinous adenocarcinoma does not adversely affect prognosis. Overall 5-year survival is 55 percent and varies with stage and grade. Patients with

appendiceal adenocarcinoma are at significant risk for both synchronous and metachronous neoplasms, approximately half of which will originate from the gastrointestinal tract.

Mucocele

An appendiceal mucocele leads to progressive enlargement of the appendix from the intraluminal accumulation of a mucoid substance. Mucoceles are of four histologic types, and

the type dictates the course of the disease and prognosis: retention cysts, mucosal hyperplasia, cystadenomas, and cystadenocarcinomas. A mucocele of benign etiology is

adequately treated by a simple appendectomy.

In a small percentage of patients, the mucocele occurs along with gelatinous ascites known as pseudomyxoma peritonei. Pseudomyxoma peritonei can be associated with either

ovarian or appendiceal mucinous tumors, usually of a malignant nature. When pseudomyxoma peritonei is present, survival is significantly decreased probably due to the

association with the ascites and malignancy. The initial surgical procedure should include cytoreductive surgery along with a right hemicolectomy for cystadenocarcinoma of the

appendix and bilateral oophorectomy, hysterectomy, and appendectomy for ovarian cystadenocarcinoma. A recent review found that even with aggressive surgical treatment, there

is a 57 percent incidence of local recurrence of pseudomyxoma peritonei from an appendiceal primary site. Once a recurrence is detected, death usually ensues from progressive

bowel obstruction and renal failure. Adjuvant therapy including radiation and intraperitoneal and systemic chemotherapy has been recommended, but its efficacy and role are

unclear.