Abstract
The author's purpose, with this study, was to determine the significance of focal hypertrophy of the internal anal sphincter on anal endosonography. Anal endosonography was performed on 40 female patients with fecal incontinence using an Acuson 128 XP/10 unit with a sector 7 MHz endorectal probe. In 22 cases, no abnormality was seen. In 12 cases, there was an isolated anterior tear of the external anal sphincter. Of these 12 cases, 2 had focal hypertrophy of the internal anal sphincter at the same location of the external anal sphincter tear. In 6 cases, combined external and internal sphincter tears were present. Sphincter tears were surgically confirmed. Focal hypertrophy of the internal anal sphincter is an indirect sign of external anal sphincter tear.