Perianal and Perirectal Abscess

Anal Abscess and Fistula-in-Ano

Infants are commonly affected with infections and abscesses in the perianal area. The vast majority of patients are male. A congenital etiology has been suggested for infant anal fistulas. A proposed relationship to androgens resulting in congenital deep, epithelialized crypts may explain the predominant occurrence in male infants.

Image 7.10 Anatomy of Surgical Anal Canal.

Infected diaper rash is the most common cause of superficial abscesses. Staphylococcal or Gram-negative enteric organisms are the most common organisms involved.

Deeper abscesses of the anal canal or perirectal tissues arise from crypt infections. Unlike in the adult population, however, the etiology in children appears to be secondary to anomalies in the crypts that predispose them to infection (Image 7.11). These infections are usually caused by enteric (e.g., coli and enterococcus) and anaerobic organisms.

Image 7.11 Acute Anal Abscess and Chronic Anal Fistula (or Fistula-in-Ano).