Maturation of the rectoanal response in premature and perinatal infants.

Twenty unselected premature and perinatal infants, and 40 older infants and children with chronic constipation were investigated manometrically. Anorectal pressure studies were found to be a safe and reliable screening method for Hirschsprung's disease. Many unnecessary deep and superficial rectal biopsies were avoided by recording a normal rectoanal response. Failure to record a normal reflex requires further evaluation by tissue diagnosis. A normal reflex does not occur in premature or perinatal infants in whom maturational age (gestational age plus age after birth) has yet to reach 39 wk, and who weigh less than 6 lb.