Lateral division of the puborectalis muscle in the management of severe constipation.

Patients with severe constipation often do not 'relax' their pelvic floor during defaecation. Electromyography of the pelvic floor may reveal inappropriate contraction during defaecation straining, and balloon expulsion, a test of rectal evacuation, may be impaired. Fifteen patients with severe idiopathic constipation and three patients with a megarectum underwent lateral division of the puborectalis muscle and upper half of the external sphincter muscle. Twelve patients had a unilateral division and six patients had both sides divided. Surgery caused a marked reduction in the maximum voluntary squeeze pressure in the anal canal from a pre-operative mean of 90 +/- 49 (s.d.) cmH2O to a postoperative mean of 40 +/- 29 cmH2O (P less than 0.0001). Four patients, three with idiopathic constipation and one with megarectum, experienced symptomatic improvement. Three of these patients had a bilateral division. Improvement did not correlate with a change in the puborectalis electromyography or the ability to expel a balloon. Three patients experienced mild mucus or urge incontinence, but no patient was incontinent for solid stool.