Anal sphincter injury after vaginal delivery in primiparous females

PURPOSE: The purpose of this study was to determine the incidence of anal s phincter injury and fecal incontinence after vaginal delivery. METHODS: Thi s was a prospective, descriptive, observational study conducted over a thre e-year period in healthy primiparous females with previously intact anal sp hincter and normal continence and without history of anorectal surgery. All patients completed a continence questionnaire and underwent endoanal ultra sound four to six weeks before and six weeks after delivery. RESULTS: Ninet y-eight primiparous females had either instrumental (vacuum or forceps) vag inal delivery (n = 23) or noninstrumental vaginal delivery (n = 75). Twenty patients, 11 (48 percent) after instrumental delivery and 9 (12 percent) a fter noninstrumental vaginal delivery, had clinical sphincter tears that re quired primary repair. Twenty-eight patients (29 percent), 19 with previous ly repaired sphincter injury, had ultrasonographic defects that involved th e external sphincter (n = 19) or both the internal and external sphincter ( n = 9). Twenty-one patients (75 percent) with ultrasonographic sphincter de fects had either major (n = 5) or minor (n = 16) fecal incontinence. CONCLU SION: Anal sphincter injuries, many of them undiagnosed at the time of deli very, are common in primiparous females after vaginal delivery, especially if vacuum or forceps are used. These injuries cause fecal incontinence in a significant proportion of the patients. Patients undergoing vaginal delive ry should be a-ware of the risks of anal sphincter injury.