Determination of Normal Anal Position Index Using a Modified Technique in Turkish Neonates

This study was aimed to determine the normal position of the anus using the anal position index (API) in an attempt to develop a more sensitive method for measuring API. To investigate API in a wide range of neonates, both term and preterm infants were included in the present study.

API was determined by measuring the anus-fourchette (FA) and anus-coccyx (AC) distance in female neonates and the anus-scrotum and AC distance in male neonates. API is defined as the ratio of the FA (scrotum) distance to the AC distance. A digital caliper was used for all measurements. The FA or scrotum and coccyx-fourchette or -scrotum distances were measured using digital calipers.

A total of 267 neonates (females, 143; males 124) were included in this study. Of these, 36 were borderline premature infants (birth at 35-37 weeks gestation) and 231 were term infants (birth at 38-42 weeks gestation). The mean API was 1.06 ± 0.04 in female and 0.90 ± 0.08 in male neonates. When premature infants were analyzed separately, the mean API was 1.12 ± 0.08 in female and 0.99 ± 0.09 in male neonates. No significant difference in API values was observed between term and preterm neonates (P < 0.05).

API values that differ from the previous studies were identified in the present study. We believe our modified method allows for more accurate measurements of the API in newborns. According to our method, the anus should be considered as anteriorly located if API is <1 in female and < 0.9 in male neonates. In addition, the present study is the first to measure API using digital calipers. Digital calipers were found to be convenient and are useful in determining the API with high accuracy (to within 0.01 cm).