The association of low imperforate anus and Down's syndrome.

Down's syndrome is the most frequent chromosomal anomaly in humans and is associated with an incidence of anorectal anomalies many times greater than that found among the general population. The anorectal malformation associated with Down's syndrome uniformly consists of a low-lying rectal pouch without a genitourinary or perineal fistula. This type of imperforate anus may often be adequately treated by simple perineal anoplasty. Since our recognition of this association, several neonates have avoided temporary fecal diversion, and several older infants with colostomies have not required anticipated pull-through procedures.