Anal sphincter function and sphincter preserving surgery

This article reviews the methods of assessing anal sphincter function and the place of sphincter-saving surgery in patients seen in the Gatrointestinal Unit of the Birmingham General Hospital between 1976 and 1984. (The main parameters for assessing sphincter function are maximinal and pressure at rest, maximum squeeze pressure, length of the high pressure zone, electromyography and parameters of rectal sensation.) Poor functional results were observed for patients having restorative surgery for rectal cancer when there is evidence of extrarectal tumour infiltration. It has now become our policy to avoid primary resection and anastomosis for fixed rectal cancer and for cancer involving the side walls of the pelvis. We would also question the value of low sphincter-saving surgery in patients with manometric evidence of a weak anal sphincter. Assessment of rectal capacity has been of predictive value in selecting patients suitable for ileorectal anastomosis in Crohn's disease. Sphincter preserving surgery in ulcerative colitis by ileorectal anastomosis or ileoanal anastomosis with pouch is unpredictable and continence is often imperfect. Repair of a rectal prolapse alone by a posterior rectopexy restores continence to 70% of patients but if incontinence persists post anal repair is beneficial in approximately 50% of cases. Incontinence which does not improve with medical therapy can often be restored by surgical treatment. Post anal repair restores continence to approximately 70% of cases and sphincter reconstruction to 80%.