In infants, the appendix is a conical diverticulum at the apex
of the cecum, but with differential growth and distention of the
cecum, the appendix ultimately arises on the left and dorsally approximately
2.5 cm below the ileocecal valve. The taeniae of the colon converge
at the base of the appendix, an arrangement that helps in locating
this structure at operation. The appendix is fixed retrocecally
in 16% of adults and is freely mobile in the remainder.
The appendix in youth is characterized by a large concentration
of lymphoid follicles that appear 2 weeks after birth and number
about 200 or more at age 15. Thereafter, progressive atrophy of
lymphoid tissue proceeds concomitantly with fibrosis of the wall
and partial or total obliteration of the lumen.
If the appendix has a physiologic function, it is probably related
to the presence of lymphoid follicles. Reports of a statistical
relationship between appendectomy and subsequent carcinoma of the
colon and other neoplasms in humans are not supported by controlled
Schumpelick V et al: Appendix and cecum. Embryology,
anatomy, and surgical applications. Surg Clin North Am 2000;80:295.
- Abdominal pain.
- Anorexia, nausea and vomiting.
- Localized right lower quadrant abdominal tenderness.
- Low-grade fever.
Approximately 7% of people in Western countries have
appendicitis at some time during their lives, and about 200,000 appendectomies
for acute appendicitis are performed annually in the United States.
The incidence has been steadily dropping over the past 25 years,
however, while the incidence in developing countries—which
in the past has been quite low—has been rising in proportion to
economic gains and changes in lifestyle.
Obstruction of the proximal lumen by fibrous bands, lymphoid
hyperplasia, fecaliths, calculi, or parasites has long been considered
to be the major cause of acute appendicitis, though that theory is
doubted by many experts. Evidence of temporal and geographic clustering
of cases has suggested a primary infectious etiology. A fecalith
or calculus is found in only 10% of acutely inflamed appendices.
As appendicitis progresses, the blood supply is impaired by bacterial
infection in the wall and distention of the lumen by pus; gangrene
and perforation occur at about 24 hours, though the timing is highly
variable. Gangrene implies microscopic perforation and bacterial
peritonitis (which may be localized by adhesions from nearby viscera).
Acute appendicitis has protean manifestations. It may simulate
almost any other acute abdominal illness and in turn may be mimicked
by a variety of conditions. Progression of symptoms and signs is the
rule—in contrast to the fluctuating course of some other
Typically, the illness begins with vague midabdominal discomfort
followed by nausea, anorexia, and indigestion. The pain is persistent
and continuous but not ...