The effect of posterior rectopexy on fecal continence. A prospective study. Twenty-three patients with rectal prolapse or intussusception were studied to specifically focus on the effect of posterior rectopexy on fecal continence, anal pressure, and rectal capacity. Before operation, five patients were fully continent (A), 10 were continent for solid stools (B) and eight patients were fully incontinent (C). Group A remained fully continent; continence was regained nine times in group B and in group C, three patients regained full continence, two became continent for solid stools, three patients remained incontinent. Other symptoms such as constipation, false urgency, and a feeling of incomplete evacuation were not beneficially influenced by rectopexy. The patients' continence status was correlated to anorectal manometry and rectal capacity measurement. In group B, incremental pressure (P = squeeze - basal P) increased significantly (P less than 0.02) as well as incremental volume (V = maximum tolerated volume - volume of first sensation) (P less than 0.05). We conclude that, by an increase of incremental anal pressure and incremental rectal volume, posterior rectopexy offers an 83 percent chance of regaining full continence, or a major improvement, and a 17 percent chance of stabilization of fecal incontinence. 