Does the mode of delivery predispose women to anal incontinence in the first year postpartum? A comparative systematic review.

OBJECTIVES: To assess if mode of delivery is associated with increased symptoms of anal incontinence following childbirth. DESIGN: Systematic review of all relevant studies in English. DATA SOURCES: Medline, Embase, Cochrane Library, bibliographies of retrieved primary articles and consultation with experts. STUDY SELECTION AND DATA EXTRACTION: Data were extracted on study characteristics, quality and results. Exposure to risk factors was compared between women with and without anal incontinence. Categorical data in 2 x 2 contingency tables were used to generate odds ratios. RESULTS: Eighteen studies met the inclusion criteria with 12,237 participants. Women having any type of vaginal delivery compared with a caesarean section have an increased risk of developing symptoms of solid, liquid or flatus anal incontinence. The risk varies with the mode of delivery ranging from a doubled risk with a forceps delivery (OR 2.01, 95% CI 1.47-2.74, P <0.0001) to a third increased risk for a spontaneous vaginal delivery (OR 1.32, 95% CI 1.04-1.68, P = 0.02). Instrumental deliveries also resulted in more symptoms of anal incontinence when compared with spontaneous vaginal delivery (OR 1.47, 95% CI 1.22-1.78). This was statistically significant for forceps deliveries alone (OR 1.5, 95% CI 1.19-1.89, P = 0.0006) but not for ventouse deliveries (OR 1.31, 95% CI 0.97-1.77, P = 0.08). When symptoms of solid and liquid anal incontinence alone were assessed, these trends persisted but were no longer statistically significant. CONCLUSION: Symptoms of anal incontinence in the first year postpartum are associated with mode of delivery.