Chapter 27 Appendix
Principles of Surgery Companion Handbook
|Function and Anatomy|
|Inflammation: Acute Appendicitis|
FUNCTION AND ANATOMY
Lymphoid tissue appears in the appendix 2 weeks after birth. The number of follicles peaks at 200 between ages 12 and 20 years. Secretory immunoglobulins are produced as part of gut-associated lymphoid tissues to protect the milieu interior. Appendectomy does not predispose to bowel cancer or alter the immune system. The appendix is useful but not indispensable. The base arises from the posteromedial aspect of the cecum, where three taeniae coli meet. The length and location of the free end are variable: pelvic, retrocecal, or either lower quadrant. Congenital defects are rare and clinically insignificant.
INFLAMMATION: ACUTE APPENDICITIS
Incidence Most common acute surgical condition of the abdomen. Most frequent in the second and third decades; parallels amount of lymphoid tissues in appendix. More common in males, especially during pubertal years. Overall incidence 1.3:1 male predominance. Incidence has been declining in the last several decades.
Etiology and Pathogenesis Obstruction of lumen caused by fecalith, lymphoid hypertrophy, inspissated barium, seeds, or intestinal worms. Symptomatic closed-loop obstruction develops because of the continued mucosal secretion into 0.1-mL capacity lumen and because of rapid multiplication of resident bacteria of the appendix. Distention stimulates visceral afferent pain fibers, producing vague, dull, diffuse middle and lower abdominal pain. Sudden distention may cause peristalsis with cramping. Venous pressure is exceeded, and arteriolar inflow causes vascular congestion of the appendix, with reflex nausea. Serosal engorgement inflames the parietal peritoneum with shift or more severe pain to the right lower quadrant. Mucosal compromise allows bacterial invasion, with consequent fever, tachycardia, and leukocytosis. With progressive distention, antimesenteric infarction and perforation occur. Occasionally, episodes of acute appendicitis resolve if obstruction is relieved; subsequent pathologic examination reveals thickened, scarred appendiceal wall.
Clinical Manifestations Symptoms Classic progression of symptoms includes anorexia (almost all have it), followed by constant moderate periumbilical pain with shift in 46 h to sharp right lower quadrant pain. Variable position of the tip of the appendix or malrotation allows variability in pain location. Subsequent episodes of emesis may occur with obstipation or diarrhea, particularly in children.
Signs Determined by the position of the appendix and whether ruptured. Vital signs show mild tachycardia or temperature elevation of 1°C. Position of comfort is fetal or supine with legs drawn up, especially right. Positional movement causes pain. Anterior appendix gives maximal tenderness, guarding, and rebound at McBurney's point (one-third the distance from the anterosuperior iliac spine to the umbilicus). Cutaneous hyperesthesia may be present early in the area supplied by right spinal nerves T10, T11, and T12. Rovsing's sign (pain in the right lower quadrant with palpation in the left lower quadrant) indicates peritoneal irritation. Psoas sign (slowly extending the patient's right thigh when lying on the left side) demonstrates nearby inflammation when stretching the iliopsoas muscle. Obturator sign (passive internal rotation of the flexed right thigh with patient supine) indicates irritation near the obturator internus. A retrocecal appendicitis may present with flank pain. A pelvic appendicitis may give pain on rectal examination with pressure on the cul-de-sac of Douglas.
Laboratory Findings Mild leukocytosis of 10,00018,000/mm3 with moderate polymorphonuclear predominance. Pyuria is present when the inflamed appendix lies near the ureter or bladder. Bacteriuria indicates urinary tract infection.
Radiography Radiographs rarely are helpful. Plain abdominal films may show a nonspecific bowel gas pattern. A fecalith in the right lower quadrant is suggestive of appendicitis. Gentle barium enema shows nonfilling of the appendix and mass effect on the medial and inferior borders of the cecum; complete filling of the appendix rules out appendicitis. Graded compression sonography may reveal a noncompressible appendix, 6 mm or greater in the anteroposterior direction. Computed tomographic (CT) scan is useful, especially with suspected abscess. Chest radiography rules out right lower lung field disease, which may simulate right lower quadrant pain by irritating T10, T11, and T12 nerves.
Laparoscopy can be diagnostic and therapeutic, especially in females to rule out gynecologic pathology. Laparoscopic appendectomy is possible.
ComplicationsRupture Rupture occurs after unrelenting obstruction of the lumen leads to gangrene distal to the occlusion. Usually occurs distal to a fecalith. Spillage is contained locally in 95 percent of patients. A phlegmon of inflamed, matted loops of intestine and omentum may resolve or may expand in contained fashion to form a periappendiceal abscess or to cause intestinal obstruction.
Incidence Rupture is present in 1525 percent of patients at presentation, with a higher incidence in pediatric and geriatric age groups.
Diagnosis Abdominal pain occasionally (only 4 percent) lessens temporarily after rupture because of sudden relief of distention; in most patients, pain continues unabated. A tender, boggy mass may be palpable on rectal examination in the right lower quadrant. Degree of distention, ileus, fever, tachycardia, leukocytosis, and toxic appearance parallel the severity of peritonitis. Temperature rise and degree of leukocytosis are markedly higher than with simple appendicitis.
Differential Diagnosis That of the acute abdomen. Preoperative diagnosis of acute appendicitis should be 85 percent accurate depending on the location of the appendix, the length of the symptoms, and the age and sex of the patient.
Acute Mesenteric Adenitis Most often in childhood, recent upper respiratory infection, generalized lymphadenopathy.
Acute Gastroenteritis Generally viral etiology; associated vomiting, diarrhea, cramping, and relaxation between hyperperistaltic waves. Salmonella gastroenteritis results from ingestion of contaminated food; historically disables groups of patients. S. typhosa infection is rare, characterized by rash, inappropriate bradycardia, leukopenia, and positive stool cultures.
Diseases of the Male The diseases that mimic abdominal pain are testicular torsion, epididymitis, and seminal vesiculitis.
Meckel's Diverticulitis Same preoperative picture as appendicitis. Requires diverticulectomy, occasionally bowel resection.
Intussusception Most under 2 years of age, currant jelly stool, intermittent crampy attacks of pain, right lower quadrant sausage-shaped mass. Initial attempt at reduction by barium enema.
Acute Ileitis or Regional Enteritis Associated with diarrhea and often a chronic history, but infrequency of anorexia, nausea, and emesis. If found at laparotomy, incidental appendectomy is indicated to decrease subsequent confusing symptoms (not done if the cecum is involved because of the greater risk of postoperative fistula).
Perforated Peptic Ulcer Right gutter spillage of upper gastrointestinal contents with rapid sealing of perforation causes prominence of right lower quadrant symptoms.
Diverticulitis or Perforating Carcinoma of the Colon Requires exploration.
Epiploic Appendagitis Infarction secondary to torsion. Pain present but no peritonitis or obstruction.
Urinary Tract Infection Right costovertebral angle tenderness and bacteriuria present.
Ureteral Stone Hematuria and referred pain to scrotum or labia present. Pyelography confirms diagnosis.
Primary Peritonitis Treated with antibiotics after paracentesis shows simple gram-positive flora.
Henoch-Schönlein Purpura Occurs several weeks after streptococcal infection; associated with purpura, joint pains, and nephritis.
Yersiniosis Transmitted via contaminated food; mimics appendicitis. Campylobacter jejuni causes diarrhea and pain with positive stool cultures.
Gynecologic Disorders Pelvic inflammatory disease, usually bilateral, associated with lower pelvic pain and cervical motion tenderness, occurs perimenstrually; Gram stain of vaginal discharge often shows gram-negative diplococci. Ruptured graafian follicle mimics appendicitis with spillage of sufficient blood and fluid into pelvis; occurs at ovulation (Mittelschmerz). Ovarian torsion, endometriosis, ruptured ectopic pregnancy. Laparoscopy is useful in diagnosis.
Others Foreign-body bowel perforations, mesenteric vascular occlusion, right lower chest pleuritis, acute pancreatitis, hematoma of abdominal wall.
Faster progression of disease with high fever and emesis and more frequent rupture at diagnosis (1550 percent).
Deceptively mild clinical course with increased morbidity because of higher incidence of concomitant disease and higher perforation rate.
Expected frequency for age group. Diagnosis more difficult because the appendix is displaced cephalad and lateral by gravid uterus; pain, nausea, and leukocytosis are common in normal pregnancy, but a left shift indicates an acute process. Maternal mortality is negligible. Fetal mortality overall is 28.5 percent, 20 percent with appendiceal perforation and peritonitis. Operation carries 1015 percent risk of premature labor.
AIDS OR HIV INFECTION
Clinical presentation no different, although leukocytosis may be absent. Cytomegalovirus enteritis, tuberculosis, or lymphoma of distal ileum can mimic appendicitis.
Treatment is always operative because the obstructed lumen will not resolve with antibiotics alone. Acute appendicitis without rupture is treated with immediate appendectomy after the medical evaluation is complete. Ruptured appendicitis with local peritonitis or phlegmon is operated on early after resuscitation for fluid and electrolyte losses. Ruptured appendicitis with spreading peritonitis requires more extensive fluid resuscitation, but the patient should undergo operation normally within 4 h to prevent continued peritoneal contamination.
Ruptured appendicitis with periappendiceal abscess formation may be treated acutely with operation, but this is associated with increased morbidity. If symptoms are of several days' duration, subsiding, and associated with right lower quadrant mass, initial nonoperative therapy with fluid resuscitation, bowel rest, and large doses of antibiotics is appropriate, possibly in conjunction with ultrasound-guided abscess drainage. If vital signs, leukocytosis, and abdominal signs progress, drainage of abscess may be indicated, followed by conservative therapy. Interval appendectomy in 6 weeks to 3 months is advised, although the overall rate of recurrence without interval appendectomy ranges from 037 percent.
Preoperative antibiotics lower infectious complications, but the regimen is controversial. If simple acute appendicitis, there is no benefit to more than 24 h of antibiotics. If perforated or gangrenous, antibiotics are given until the patient is afebrile and the white blood cell count is normal. Pathogens in acute appendicitis are mixed colonic flora, both aerobic and anaerobic; Bacteroides fragilis needs coverage. Clindamycin plus an aminoglycoside or a second-generation cephalosporin regimen is popular.
Procedure Incision should be in the right lower quadrant for patients with suspected appendicitis. A McBurney (oblique) or a Rocky-Davis (transverse) muscle-splitting incision is most common. If an abscess is suspected, a lateral incision is used to prevent peritoneal contamination. A lower midline incision is used if the diagnosis is in question. A lower midline incision also is used for general exploration but is contraindicated with abscess because infected material must be brought through the uncontaminated peritoneal cavity.
The appendiceal stump can be simply ligated or ligated with purse-string or Z-stitch inversion. If appendicitis is not found, the pelvic organs and remaining abdominal viscera are explored. The mesentery is examined for lymphadenitis. The ileum is run for terminal ileitis or Meckel's diverticulitis.
Drainage of localized pus is accomplished with lateral drains. The peritoneal cavity cannot be drained. If the appendix is ruptured, subcutaneous fat and skin are left open to heal by granulation or secondary closure. Primary wound closure is almost always used in children.
Appendectomy can be performed by the laparoscopic approach. This is especially suited to women in whom a differential diagnosis of gynecologic disease is entertained. Obese patients may benefit from the laparoscopic approach. Intracorporeal stapling devices are used to divide the mesoappendix and the appendiceal base.
Mortality is 0.1 percent if unruptured acute appendicitis, 3 percent if ruptured, and 15 percent if ruptured in the elderly. Death usually is from sepsis, pulmonary embolism, or aspiration; improving rates are seen with earlier diagnosis before rupture and better antibiotics.
Morbidity is increased with rupture and older age. Early complications are septic. Wound infection requires reopening of the skin incision, which predisposes to dehiscence (less common with muscle-splitting incision). Intraabdominal abscesses may occur from peritoneal contamination after gangrene and perforation. Fecal fistula results from necrosis of a portion of the cecum by an abscess or constricting purse-string suture or from a slipped ligature. Intestinal obstruction may occur with loculated abscesses and adhesion formation. Late complications include adhesion formation with mechanical obstruction and hernia.
Neoplasms are uncommon. Benign lesions may cause obstruction with acute appendicitis. Malignant tumors total less than 1 percent.
Carcinoid tumors of the gastrointestinal tract are found most commonly in the appendix (4575 percent). Only 3 percent of these metastasize, and even fewer produce malignant carcinoid syndrome. Three-fourths present in the distal third of the appendix as small, firm, circumscribed, yellowish-brown tumors. If confined to appendix and less than 2 cm, treatment is with appendectomy and wide resection of mesoappendix; if greater than 2 cm, a right hemicolectomy is used.
Adenocarcinoma usually is discovered incidentally at appendectomy and behaves like colon carcinoma. Treatment is with right hemicolectomy.
Mucocele is a cystic dilatation of the appendix containing mucoid material. Appendectomy is the treatment for benign (retention cysts, mucosal hyperplasia, cystadenoma) or malignant (mucous papillary adenocarcinoma) lesions. Rupture or iatrogenic spillage results in pseudomyxoma peritonei.
For a more detailed discussion, see Kozar RA, Roslyn JJ: Appendix, chap. 27 in Principles of Surgery, 7th ed.
Copyright © 1998 McGraw-Hill
Seymour I. Schwartz
Principles of Surgery Companion Handbook