Usual anal position is described to be midway between the vaginal fourchette (scrotum) and the coccyx. Anal position index (API) is a simple method to evaluate anal position in the subjects. Bar-Maor and Eitan(1) were the first to describe this objective measurement as anogenital index that was later called API by Reisner, et al.(2). Positive correlation has been described between anterior displacement of anus and constipation at birth(3).

Three hundred and eighty seven children born at or attending the well baby clinic of the hospital were included in the study after obtaining consent from the parents.

Using the method described by Genc, et al.(4) anal position index was calculated as the ratio of anus-fourchette distance to coccyx-fourchette distance for females and anus-scrotum distance to coccyx-scrotum distance for males.

There were 300 males and 87 females in the study. It included 31 neonates, 313 infants and 43 children between 1-3 years of age. Mean API in males was found to be 0.43 (S.D. ± 0.05) while in the females the value was 0.37 (S.D. ± 0.06). Anterior displacement (Mean + 2 S.D.) was present in 16 males and one female. There was no significant correlation of API with age, height and weight of the subjects. Children with anterior displacement of the anus did not give any history of constipation.

Anterior anus, anteriorly displaced anus, anterior ectopic anus, anteriorly located anus or short perineal body are synonyms for the same anomaly. It is believed to be due to malformation of the mid-portion of the external sphincter and weakness of corres-ponding segment of the anal canal(5). It is a controversial entity; however, several investigators claim it to be major cause of constipation. Leape, et al.(3) diagnosed the condition on the basis of clinical inspection alone. Bar-Maor and Eitan(1), Reisner et al(2) and Genc, et al.(4) determined API using various methods. There was no difference in the index in the newborns and the older children. Although Genc, et al.(4) did not find any correlation between location of the anus and constipation, surgical correction of the anomaly has been advocated for constipation due to anterior ectopic anus(3,5).

In the present study, API was found to be lower than that reported in the western literature. It could be due to lower body weight in our population or different technique used for measurement. We also did not find any positive correlation between anal position and constipation. We advocate that the children with abnormal anal position index alone should not be the sole indicator for surgical intervention and they should be kept under follow up for development of constipation and appropriate treatment after proper evaluation at that time.

Funding: Indian Council of Medical Research.

Anup Mohta,
Mamta Rani Goel,
GTB Hospital and University College
 of Medical Sciences,
Delhi 110 095, India.

1. Bar-Maor JA, Eitan A. Determination of the normal position of the anus (with reference to the idiopathic constipation). J Pediatr Gastro-enterol Nutr 1987; 6: 559-561.

2. Reisner SH, Nitzan M. Determination of anterior displacement of the anus in the newborn infants and children. Pediatrics 1984; 73: 216-217.

3. Leape LL, Ramenofsky ML. Anterior ectopic anus: A common cause of constipation in children. J Pediatr Surg1978; 13: 627-630.

4. Genc A, Taneli C, Tansug N, Kasirga E, Yilmaz D, Kucukoglu T, et al. Evaluation of the location of the anus by a modified technique in the neonate. J Pediatr Surg 2002; 37: 80-82.

5. Upadhyaya P. Mid-anal sphincteric malforma-tion, cause of constipation in anterior perineal anus. J Pediatr Surg 1984; 19: 183-186.