Constipation is a major functional complication after internal sphincter-saving posterior sagittal anorectoplasty for high and intermediate anorectal malformations.

Anorectal function was clinically, manometrically, and radiologically followed-up in 40 patients who underwent an internal sphincter-saving posterior sagittal anorectoplasty in 1984 to 1989. The functioning internal sphincter was manometrically verified in 83% (33/40) of the patients. Soiling related to sphincter insufficiency was found in only 4 of the 33 patients with a functioning internal sphincter; 5 of the 7 patients without an internal sphincter had soiling. Symptomatic constipation was found in 73% (24/33) of the patients with a functioning internal sphincter, but in only 28% (2/7) of the patients without this structure. Constipation was not associated with a stenotic anal outlet in any patient. On anorectal manometry, there was no statistical difference in basal and pressures and internal sphincter reflex threshold values between constipated and nonconstipated patients. Histologically, ganglion cells were found in the proximal anal canal in all cases. The radiological size of the rectal pouch before closure of the protecting colostomy had a positive correlation with the severity of constipation. Medical treatment with diet and bulk-laxatives (13 patients) or with stimulant laxatives and occasional enemas (11 patients) successfully relieved constipation in 24 patients. In 2 patients, the symptoms were refractory to medical treatment and a resection of the megarectum was required. In conclusion, the preservation of the internal sphincter in patients with high or intermediate anorectal anomalies gives a good fecal continence outcome, but is associated with a high incidence of symptomatic constipation.