[Imperforate anus. Various Belgian epidemiologic data].

Two hundred and ninety cases of congenital anorectal anomalies were collected in a survey of the experience contributed by belgian surgeons over the last ten years (1971-1980). The incidence (1 in every 4,500 live births) and the sex ratio (56% males, 44% females) are similar to accepted figures in white race; this suggests that most of the cases have been included in the survey. The collected series was analysed according to the international classification proposed in 1970. It differs from most reported series 1 degrees in boys by the prevalence (58%) of low, infralevator types and the unusually high frequency of recto-vesical fistulas (versus recto-urethral); 2 degrees in girls, by the very high prevalence (80%) of low types and a relatively heavy incidence of low recto-vaginal fistulas (versus recto-vestibular). These characteristics could be partly related to a lack of accuracy in the diagnostic work-up. Every new case of anorectal anomaly should be accurately described and classified since the choice of surgical approach and the functional result are related to a large extent to the type and the level of the malformation. Use of the international classification is recommended.