Obstetric risk factors for anorectal dysfunction after delivery: a systematic review and meta-analysis

Pregnancy and childbirth are considered risk factors for pelvic floor dysfunction, including anorectal dysfunction. We aimed to assess the effect of obstetric events on anal incontinence and constipation after delivery.

We systematically reviewed the literature by searching MEDLINE, Embase and CENTRAL. We included studies in women after childbirth examining the association between obstetric events and anorectal dysfunction assessed through validated questionnaires. We selected eligible studies and clustered the data according to the type of dysfunction, obstetric event and interval from delivery. We assessed risk of bias using the Newcastle Ottawa Scale and we performed a random-effects meta-analysis and reported the results as odds ratios (ORs) with their 95% confidence intervals. Heterogeneity across studies was assessed using I² statistics.

Anal sphincter injury (OR: 2.44 [1.92-3.09]) and operative delivery were risk factors for anal incontinence (forceps-OR :1.35 [1.12-1.63]; vacuum-OR: 1.17 [1.04-1.31]). Spontaneous vaginal delivery increased the risk of anal incontinence compared with caesarean section (OR: 1.27 [1.07-1.50]). Maternal obesity (OR:1.48 [1.28-1.72]) and advanced maternal age (OR: 1.56 [1.30-1.88]) were risk factors for anal incontinence. The evidence on incontinence is of low certainty owing to the observational nature of the studies. No evidence was retrieved regarding constipation after delivery because of a lack of standardised validated assessment tools.

Besides anal sphincter injury, forceps delivery, maternal obesity and advanced age were associated with higher odds of anal incontinence, whereas caesarean section is protective. We could not identify obstetric risk factors for postpartum constipation, as few prospective studies addressed this question and none used a standardised validated questionnaire.