Anal endosonographic findings in patients with obstructed defecation.

Anal endosonography, including measurements of anal sphincter size, was performed in 16 patients with obstructed defecation. The findings were compared with those at defecography and anal manometry. Patients with rectocele and intussusception had a normal endosonographic appearance. One patient with puborectalic spasm had normal sonography. There was no correlation between sphincter size and anal manometry. The external sphincter muscle was thicker and the cross-sectional area larger in patients with obstructed defecation than in healthy controls (p < 0.05). Two patients with sphincter spasm and impaired rectal emptying at defecography had clearly thickened internal sphincters which may be the cause of their defecatory disorder. Three patients with previous anal dilatation or hemorrhoidectomy had sphincteric defects. Anal endosonography may be considered in patients with obstructed defecation to identify patients with internal sphincter hypertrophy.