Obstetric sphincter injury interacts with diarrhea and urgency to increase the risk of fecal incontinence in women with irritable bowel syndrome.

Objectives: This study aimed to confirm that fecal urgency and diarrhea are independent risk factors for fecal incontinence (FI), to identify obstetrical risk factors associated with FI in women with irritable bowel syndrome, and to determine whether obstetric anal sphincter injuries interact with diarrhea or urgency to explain the occurrence of FI.

Methods: The study is a supplement to a diary study of bowel symptoms in 164 female patients with irritable bowel syndrome. Subjects completed daily bowel symptom diaries for 90 consecutive days and rated each bowel movement for stool consistency and presence of urgency, pain, and FI. All female participants from the parent study were invited to complete a telephone-administered 33-item bowel symptom and obstetric history questionnaire, which included the fecal incontinence severity index.

Results: Of the 164 women in the parent study, 115 (70.1%) completed the interview. Seventy-four (45.1%) reported FI on their diary including 34 (29.6%) who reported at least 1 episode per month, 112 (97.4%) reported episodes of urgency, and 106 (92.2%) reported episodes of diarrhea. The mean fecal incontinence severity index score was 13.9 (9.7). On multivariable analysis, FI was significantly associated with parity (P = 0.007), operative abdominal delivery (P = 0.049), obstetrical sphincter lacerations (P = 0.007), fecal urgency (P = 0.005), diarrhea (P = 0.008), and hysterectomy (P = 0.004), but was not associated with episiotomy, pelvic organ prolapse, or urinary incontinence. The synergistic interactions of obstetric anal sphincter laceration with urgency (P = 0.002) and diarrhea (P = 0.004) were significant risk factors for FI.

Conclusions: Fecal urgency and diarrhea are independent risk factors for FI, and they interact with obstetric anal sphincter laceration to amplify the risk of FI.