What is an acute appendicitis?

Inflammation in the right lower quadrant was considered a nonsurgical disease of the cecum (typhlitis or perityphlitis)until Fitz recognized acute appendicitis as a distinct entity in 1886. Appendiceal inflammation is associated with obstruction in 50 to 80% of cases, usually in the form of a fecalith and less commonly, a gallstone, tumor or ball of worms. Continued secretion of mucinous fluid in the obstructed viscus presumably leads to a progressive increase in intraluminal pressure sufficient to cause eventual collapse of the draining veins. Ischemic injury then favors bacterial proliferation with additional inflammatory edema and exudation, further embarassing the blood supply. Nevertheless, a significant minority of inflamed appendices have no demostrable luminal obstruction, and the pathogenesis of the inflammation remains unknown.

Acute apendicitis is mainly a disease of adolescents and young adults, but it may occur in any age group and affects males slightly more often that females. Classically acute appendicitis produces the following manifestations, in the sequence given:

• pain, at first periumbilical but then localizing to the right lower quadrant
• nausea or vomiting
• Abdominal tenderness, particularly in the region of appendixmild fever
• An elevation of the peripheral white blood cell count up to 15,000 to 20,000 cell/mm3

Regretably, this classic presentation is more often absent than present. Although pains, nausea, and vomiting usually develop, tenderness may be deceptively absent or maximal in atypical locations. In some cases, a retrocecal appendix may generate right flank or pelvic pain, whereas a malrotated colon may give rise to appendicitis in the left upper quadrant. The peripheral leukocytosis may be minimal or so high as to suggest alternative diagnoses. Nonclassic presentations are encountered more often in young children and in the very elderly, populations with a host of other plausible abdominal emergencies.