The Anal Position Index: A Simple Method to Define the Normal Position of the Anus in Neonate

Abstract

Background: The purpose of this study was to determine the normal position of anus using anal position index (API) and the modified measurement method and also to emphasize the importance of ectopic anus. Methods: This cross-sectional study was performed on 400 neonates, equally boys and girls, who were all full term and delivered without any malformations. Anal position index, which is the ratio of anus-fourschette distance in girls and anus-scrotum distance in boys to the distance between coccyx and fourschette/scrotum, was calculated in all cases. To make correct measurements, transparent adhesive tape was used longitudinally on midperinum in a way that it covered the anus. Then fourschette/scrotum, anus center, and the lower margin of coccyx were marked on it. Distances marked on each tape were then measured with the standard ruler. Results: Mean±SD of API in girls was 0.45±0.005 (95%CI: 0.44-0.46) and in boys was 0.54±0.005 (95% CI: 0. 53-0.55). Mean±2SD was considered as the normal range for an anus position. Six female and five male neonates who had abnormal APIs were put through more investigations. Conclusion: Our findings suggest a simple method for determination of normal position of anus in children; especially those who referred for chronic constipation. API can never be considered as the sole indication for the surgical intervention.
Keywords: ectopic anus, anal position,constipation.