Thickening of the Internal Anal Sphincter: Primary Cause or Secondary Effect of Constipation

Constipation is one of the most common abdominal symptoms in childhood. In many cases, no primary cause is found and the condition may be labelled as “idiopathic constipation”. Fortunately, most of these cases respond well to dietary manipulation and laxatives. However, some patients continue to suffer from severe refractory constipation without an obvious primary cause [1]. As pediatric surgeons, our main concern is to identify an unrecognized correctable surgical etiology. Among these overlooked potentially correctable surgical causes, internal anal sphincter (IAS) achalasia refers to failure of relaxation of the internal anal sphincter after rectal distension [2].