Anorectal congenital malformations, and their associations in a Chilean University Hospital between 1979 and 1999

Background: Anorectal atresia is a relatively frequent malformation in the newborn. According to the Latin American Collaborative Study for Congenital Malformations (ECLAMC), its frequency is 4.1 per 10,000 born alive. Aim: T o determine the frequency of anorectal malformations at birth, and compare the figures with those of other maternity hospitals in Chile participating in ECLAMC, with the figures of the whole ECLAMC and with figures from other worldwide monitoring systems. Patients and methods: All births occurred in the University of Chile Clinical Hospital between January 1979 and August 1999, were reviewed. Results: During the study period, 70,242 children were born, 4,486 had a malformation and 54 had an anorectal malformation (7.7 p er 10,000 born alive). Fifty nine percent had other associated malformation s (of the urinary tract in 42.5%, skeletal in 26% and cardiovascular in 18. 5%). Five stillborn babies had other severe malformations. Twenty one child ren had a fistula. Forty three % were male, 39% female and 18% had ambiguou s sex. When compared with normal controls, malformed newborns had a lower b irth weight, lower gestational age and a higher mean maternal age, a higher frequency of metrorrhagia during the first trimester of pregnancy, a highe r number of siblings with malformations and a higher degree of consanguinit y among parents. Conclusions: The participation of recessive genes in the e tiology of anorectal malformations is suggested.