Anterior displacement of anus: A common association with constipation in infancy

Abstract

Background: Anterior displacement of the anus (ADA), a common congenital abnormality of anorectal region, has been recognized as a common cause of constipation. However, the more recent studies have failed to demonstrate an association between the anterior displacement and constipation self. Objective: Investigate the association between ADA and constipation. Methods: Four hundred and three neonates have been examined and their anal position index (API) has been determined. API less than 0.46 and 0.34 in males and females, respectively, is defined as ADA. A 6-month prospective cohort study has been conducted to evaluate the association between ADA and constipation. Results: Overall incidence of ADA is 24.8%, while the incidence is significantly higher in females than males (32.0% and 17.7%, respectively; p <0.01). Compared to the first child, later birth order, especially the second child, trends to have an increased risk of ADA (Odd ratio=1.75; 95%CI=1.06-2.90). Average maternal age of ADA is higher than control (28.2 and 26.6 years, respectively; p=0.02). Overall incidence of constipation is 10.1% without any difference between ADA group and control (12.0 and 9.5%, respectively). Nevertheless, at six months incidence of constipation is higher in ADA than in control (6.7% and 0.8%, respectively; p < 0.01). The incidences of ADA in infants with constipated events at 2, 4 and 6 months of age are 10.0%, 33.3%, and 71.4%, respectively. Conclusion: ADA is a common finding with reported incidence of one-quarter of neonates. Female genre, later birth order and higher maternal age are risk factors of ADA. Children with ADA have an increased tendency toward constipation corresponding with increasing age. API measurement during pediatric examination is recommended to achieve a complete evaluation of infancy constipation.