The anal sphincter force in the evaluation of postoperative imperforate anus.

Eight-four children, all of whom had imperforate anus, were evaluated by measuring the anal sphincter force (ASF). Sixty-three were boys, 46 of whom had a high imperforate anus and 17 of whom had the low anomaly. There were 7 girls with cloacal malformations, 7 girls with high type and 7 with low type of malformation. In all the boys with a high imperforate anus the ASF ranged from 50 to 300 g. Those boys with a low type had an average ASF of 513 g. Normal values vary from 480 to 600 g. Twenty-five of the boys with a high imperforate anus had undergone posterior sagittal anorectoplasty and none were clinically continent. Their ASF measurements were lower than in patients with spina bifida. Patients with a low anomaly, both boys and girls, were continent and had high ASF readings. The ASF is a simple, inexpensive, and objective measurement of fecal incontinence when this is the consequence of muscular inadequacy. A reproducible quantification is now available to compare results of different operations and different centres.