Comparison of anterior sphincteroplasty and postanal repair in the treatment of idiopathic fecal incontinence. Both postanal repair and anterior sphincteroplasty with levatorplasty have been advocated in the treatment of idiopathic fecal incontinence. To assess the functional results of these procedures, physiologic and radiologic measurements were carried out prospectively in 33 patients with idiopathic incontinence undergoing operative treatment, and 12 age- and sex-matched controls. Sixteen patients had anterior sphincteroplasty and levatorplasty and 17 had postanal repair. A satisfactory postoperative outcome was defined as perfect continence or incontinence of flatus only. Ten patients in the anterior sphincteroplasty group had satisfactory results (64 percent) and 10 in the postanal repair group (59 percent). Preoperatively, both groups had decreased resting and squeeze pressures, impaired and mucosal electrosensitivity, and marked pelvic descent vs. controls. Postoperatively, significant improvement in sphincter pressures and mucosal electrosensitivity was seen in both groups. No significant change in anorectal angle was demonstrated in the postanal repair group, whereas it was made significantly more obtuse in the anterior sphincteroplasty group. It is likely that the improved continence resulting from either of these two procedures is secondary to better anal sphincter muscle function and improved and sensation. It would appear that the anorectal angle is not crucial in maintaining continence. 