Postoperative internal sphincter function in anorectal malformations — a manometric study

An anorectal manometric assessment of 30 patients with operated high or intermediate anorectal malformations was performed in order to study internal sphincter function in the reconstructed anal canal. In 14 patients (group I, mean age 3.1 years) the rectal blind pouch and fistula, when present, were used in the reconstruction of the anal canal by posterior sagittal anorectoplasty (12 cases) or sacroperineal pull-through (2 cases). In 16 cases (group II, mean age 8.8 years) the anal canal was reconstructed from proximal rectum or sigmoid by sacroabdominoperineal pull-through. In 11 of the 14 patients in group I manometric findings suggested the presence of a functioning internal sphincter. The pattern of anal slow-wave activity and rectoanal inhibitory reflex was normal. None of the patients in group II had a rectoanal inhibitory reflex and the slow-wave activity was of a colonic type. The resting anorectal pressure profiles were significantly higher in group I than in group II (mean 38 cm H₂O vs. 25 cm H₂O). The fecal continence of patients in group I was superior to those in group II despite their much younger ages. The findings of this study indicate that in anorectal malformations there is internal sphincter function in the distal rectal blind pouch and that it can and should be preserved when the anal canal is reconstructed.