Anteriorly displaced anus: an under-recognized cause of chronic constipation

Abstract

Anterior displacement of a normal anus is recognized as a cause of severe constipation in some children. We have reviewed our experience with 13 children treated for this disorder over the past 8 years at the University of Virginia Health Sciences Center. Twelve of the patients were female and the age at the time of operation ranged between 12 months and 9 years. In all patients constipation began in the first 3 to 6 months of life. Symptoms were characterized by marked straining upon passage of stool, often accompanied by perineal pain. All patients had been unsuccessfully treated with agressive use of stool softeners and cathartics. The anus had a normal appearance, although it was located anterior to its normal position in every case. There was no evidence of anal stenosis on digital examination; in each case a large posterior rectal cul-de-sac could be palpated. A barium enema examination disclosed a prominent posterior shelf of the rectum, often with enormous dilation of the colon posteriorly. All patients underwent surgical treatment using a posterior anoplasty with advancement of the posterior rectal wall. In 10 patients a posterior rectal myomectomy was added to the procedure. Pathologic evaluation of the rectal muscle was normal in each instance. Complete relief of constipation was achieved in all patients, with follow-up extending for as long as 6 years. One patient continues to require occasional use of stool softeners. Anterior displacement of the anus is a frequently overlooked, although easily corrected, cause of severe constipation in childhood.