Anorectal endosonography in benign anorectal disorders.

Anal endosonography is an excellent method of visualising the anal sphincters and the pelvic floor. In particular, defects in the internal and external anal sphincters can be demonstrated. Thickness of the sphincters can also be measured. Fistulas and abscesses can be visualised. The clinical indications for performing anal endosonography are: (i) Faecal incontinence and soiling, to detect a possible sphincter defect. In combination with anorectal function tests (like anal manometry, rectal compliance, EMG and pudendal nerve latency measurements), the cause of faecal incontinence or soiling can be determined. (ii) Fistulae and abscesses, to detect the extension of the lesion in relation to the anal sphincters and deeper structures. (iii) Constipation, to exclude a hypertrophic sphincter. (iv) Pre- and postoperative in ileo-rectal and ileo-anal anastomosis, to demonstrate or exclude anal sphincter defects. (v) Pre- and postoperatively in all patients who undergo anorectal surgery to be informed about possible anal sphincter abnormalities. Anorectal function tests should also be performed when anal endosonography is done in evaluating possible faecal incontinence. For scientific interest all anorectal disorders like haemorrhoids, fissures and inflammatory bowel disease offer challenges to anal endosonography. In conclusion, anal endosonography is an easy to perform test of great importance in patients with anorectal pathology, especially in patients with faecal incontinence or soiling and patients who need anorectal surgery to be informed about possible sphincter defects.