Rectal bleeding due to nonspecific colitis in premature infants.

Rectal bleeding is not uncommon in newborn infants. Anal fissures are regarded as the most common cause. We report two cases in which the presence of an anal fissure delayed the diagnosis of nonspecific colitis in premature infants. Rectosigmoidoscopic and biopsy findings are discussed with regard to the heterogeneous group of disorders associated with isolated rectal bleeding in young infants. These procedures may be helpful in ruling out necrotizing enterocolitis in premature infants.