Transrectal ultrasound study of the pathogenesis of solitary rectal ulcer syndrome.

Transrectal ultrasonography is of clinical value in anorectal carcinoma and in inflammatory diseases of the anorectum. In this study a rigid linear endorectal probe was used to examine 15 patients with endoscopically and biopsy proved diagnosis of solitary rectal ulcer syndrome. In 13 of the 15 patients the rectal wall was thicker (mean (SEM) 5.7 (0.4) mm; normal values: 2.8 (0.1) mm) near the rectal ulcer. In all these cases the muscularis propria layer exceeded the maximum normal diameter of 2 mm. In nine of the 15 patients the normal rectal wall echo-structure, with five distinct layers, was disturbed and there was fading of the borders between the mucosa and the muscularis propria. Poor relaxation of the puborectalis muscle during straining was seen on ultrasound in 11 patients, as was intussusception of the rectal wall. The obvious enlargement of the muscularis propria points to a chronic mechanical load on the rectal wall. The ulcerative lesions are formed in this area of overloaded rectal wall. The direct visualisation of the puborectalis muscle during dynamic transrectal ultrasonography indicates that the fact that it does not relax is an important element in the pathogenesis of solitary rectal ulcer syndrome.