BACKGROUND: Anal incontinence is a major concern following delivery with obstetric anal sphincter injury and has been related to the degree of sphincter tear.

OBJECTIVES: To 1) evaluate whether women with a fourth degree obstetric anal sphincter injury in the first delivery have an increased risk of long-term anal- and fecal incontinence after a second delivery and 2) assess the impact of mode of second delivery on anal incontinence and related symptoms in these patients.

STUDY DESIGN: We performed secondary analyses of a national questionnaire study in all Danish women with an obstetric anal sphincter injury in their first delivery and one subsequent delivery, both deliveries in 1997-2005. The questionnaires were sent minimum 5 years since the second delivery. In Denmark, women with anal incontinence after a delivery with OASIS are recommended elective cesarean in subsequent pregnancies. We performed uni- and multivariable logistic regression analyses to evaluate the outcomes.

RESULTS: In total, 2,008 patients had an obstetric anal sphincter injury of which 12.2% (n=245) had a fourth degree tear in the first delivery. The median follow-up time since the first delivery with OASIS was 11.6 years (IQR 10.2-13.2 years) and since the second delivery 8.5 years (IQR 7.1-10.1 years). Women with a fourth degree sphincter injury in the first delivery were at higher risk of anal incontinence (58.8%, n=144) as well as fecal incontinence (30.6%, n=75) than patients with a third degree injury in the first delivery (41.0%, n=723 and 14.6%, n=258, respectively). The differences between groups persisted after adjustment for important maternal, fetal and obstetric characteristics (aOR 2.14 (95%CI 1.52-3.02) P<0.001 for anal incontinence and aOR 2.49 (95%CI 1.73-3.56) P<0.001 for fecal incontinence). In subgroup analyses of patients with fourth degree anal sphincter injury in the first delivery, mode of second delivery was not associated with the risk of anal incontinence (aOR 0.97 (95%CI 0.41-1.84) P=0.71) or fecal incontinence (aOR 1.28 (95%CI 0.65-2.52) P=0.48). The effect of mode of second delivery did not differ between those with a fourth degree obstetric anal sphincter injury and those with a third degree injury with regard to both anal- (P=0.09) and fecal incontinence (P=0.96).

CONCLUSIONS: After a second delivery, women with a fourth degree obstetric anal sphincter injury in the first delivery have a higher risk of long-term anal- and fecal incontinence than women with a third degree sphincter injury. Adjusted odds of long-term anal- and fecal incontinence did not differ significantly by mode of second delivery. Women with a fourth degree obstetric anal sphincter injury should be informed about the increased risk of long-term anal incontinence and that subsequent elective cesarean is not protective.