Thickened Internal Anal Sphincter Has Been Reported to Be a Typical Finding in Solitary Rectal Ulcer Syndrome

Figure. Endoscopic and sonographic findings of a 59-year-old woman with solitary rectal ulcer syndrome. (A) Sigmoidoscopy shows large ulcer with fold convergence (black arrow) in the lower rectum. (B) Increased thickness of internal anal sphincter is noted at mid level of anal canal. (C) Internal anal sphincter is also more thickened at low level of anal canal. TO THE EDITOR: We read with interest the original article by Sharma et al regarding the clinical characteristics of fecal evacuation disorder among patients with solitary rectal ulcer syndrome (SRUS). The study showed that SRUS patients with abnormal balloon expulsion test had thicker internal anal sphincter (IAS), compared to those with normal tests. In fact, thickened IAS has been reported to be a typical endoanal sonographic finding in SRUS. This finding could be associated with hypertrophy, possibly resulting from chronically increased work demand. A thickened IAS in patients with SRUS also is reported to be highly predictive of high-grade rectal intussusception. Therefore, the result of Sharma et al’s study is not a novel finding but adds to the body of evidence demonstrating thickened anal sphincter as a typical endoanal feature in SRUS. As far as we know, several measuring points are required for the assessment of IAS thickness, since the thickness of IAS is not uniform. However, we could not find detailed methods for the measurement of IAS thickness in their article. We present typical endoscopic and sonographic findings of SRUS in a 59-year-old woman. She was referred to our constipation clinic for refractory constipation. Colonoscopy showed large ulcer with fold convergence (Figure A). The thickness of the IAS was measured at 4 different circumferential points. Endoanal sonography demonstrated thickened IAS irrespective of the level of anal canal (Figures B and C). Pathology showed fibrous obliteration and extension of smooth muscle fibers into the lamina propria. The confirmatory diagnosis of SRUS was made based on clinical presentation, endoscopic appearance and characteristic histologic features.