To analyze the long-term effects of age, pregnancy, and vaginal delivery on the prevalence and impact of accidental bowel leakage in women.

Two simple random samples of 20,000 nulliparous and 15,000 two-para women [11,000 with a vaginal delivery (VD) and 4000 with a cesarean delivery (CD)] were retrieved from the Swedish Medical Birth Register (MBR) and the Total Population Register. Information about the prevalence and impact of accidental bowel leakage was assessed by a postal- and web-based questionnaire survey in 2015 (nullipara) and 20 years postnatally in 2014 (parous women). 18,761 women responded to the questioinnaire (response rate 54%) and participants aged 40-64 years with information on current body mass index (BMI= kg/m2) and bowel incontinence were considered eligible for a matching procedure, which resulted in 4192 nulliparous women, 6877 VDs and 2411 CDs. One-to-one matching using the exact age and ±3 BMI units was used, yielding 1961 women in each cohort. The VD cohort was used as the index for matching. The standardized mean difference for age and BMI was less than 0.1, which is considered within the threshold of imbalance. MBR data were used prospectively and linked with information from the pelvic floor symptom-specific postal- and web-based questionnaire. Fecal and anal incontinence (FI and AI) were defined according to the International Urogynecological Association (IUGA) and the International Continence Society (ICS) as accidental leakage of solid and liquid stool with and without concomitant gas leakage. AI was defined as isolated gas incontinence (IGI) or FI. Leakage frequency and impact of bowel leakage were assessed, conforming to the Jorge-Wexner incontinence score (1). The leakage frequency was stratified into "Never" (no incontinence), whereas "Less than once a month," "Several times a month," "Once a week or more,” and "Once a day or more” were defined as incontinence. Three questions measured the mental impact of AI: the frequency of the need to wear a pad and the impact of incontinence on daily lifestyle, with the same frequency categories used for FI and AI. The third question was about symptom-specific bother and dichotomized into “Not bothersome” (“No problem” and “A minor nuisance”) and “Bothersome” (“Some bother,” “Much bother,” and “A major problem”). The severity and impact of accidental bowel leakage were also assessed by the Jorge-Wexner score with a sum ranging from 0 (continent) to 20 (complete incontinence). BMI was calculated using current height and weight as reported in the questionnaire. The effect of pregnancy was interpreted as the difference between the nulliparous and CD cohorts, and the additive effect of VD was interpreted as the difference between the VD and CD cohorts. Given the size of the study cohorts, an alfa level of 0.05, and a power value of 80%, the significant odds ratio (OR) of FI was 1.32 when comparing the cohorts, provided that the prevalence of FI was 10.2% in the CD cohort. Continuous variables were presented as mean and standard deviation (SD), median, and interquartile range (Q1-Q3), and categorical data as number and percent. For pairwise comparisons, the Mantel-Haenszel Chi Square test was for ordered categorical variables and the Mann-Whitney U-test for continuous variables. The estimated age-related probability and OR with 95%CI per 10 years for FI and AI were obtained by logistic regression. No adjustment was made for multiple testing. Missing data were accounted for and excluded. Statistical significance was set at a value of P <0.05. Statistical analyses were performed using SAS version 9.4 (SAS Inc, Cary NC).

There were minor differences in the prevalence of FI between groups: 12.9% (nullipara), 10.2% (2 CDs), and 14.2% (2 VDs), although the differences were significant (nullipara vs. 2 CDs, p 0.0095 and 2 VDs vs. 2 CDs, p 0.0001)(Table). The predicted value of FI at 55 years of age was 13.9 (95%CI 11.8–16.2, nullipara), 11.2 (95%CI 10.3–13.4, 2 CDs), and 17.0% (95%CI 14.7–19.5, 2VDs) (Figure). Bothersome FI was more prevalent after 2 VDs compared with 2 CDs (4.2 vs. 3.6%, p 0.0014) and compared with nulliparous women (3.1%). AI occurred in 50.9% of nullipara and in 43.9% after two CDs (OR 1.33, 95% CI 1.17–1.50), and in 55.8% after 2 VDs (OR 1.62, 95%CI 1.42–1.83, 2 CDs vs. 2 VD) (Table). Bothersome AI was more prevalent after 2 VDs 7.0% versus 5.6% after 2 CDs (p<0.0001). The prevalence of IGI was 33.7% in women with 2 CDs and 41.6% in those with 2 VDs (OR 1.40, 95%CI 1.23–1.60). Bothersome IGI was most prevalent after VDs (2.6%) (Table). The mean Wexner score increased from 1.11 (SD 1.99) in women with 2 CDs to 1.47 (SD 2.24) after 2 VDs, p<0.0001 (Table).

The matched cohort with 2 VDs had a probability of FI at 55 years of 17% which was on par with that in the nulliparous and the 2 CDs cohort in this study. The probability of FI for the 2 VDs cohort was similar to that in a recent study on 2-para vaginally delivered women with no, one, and two OASIs (2). At 55 years of age, the prevalence of FI was 15.5% (no OASI), 25.8% (one OASI), and 39.8% after two OASIs (2). These results strongly suggest that OASI, rather than pregnancies per se or uncomplicated vaginal deliveries, is the primary factor contributing to long-term fecal incontinence in women after childbirth.

The findings of this study support the implementation of a bundle of care, i.e. evidence-based practices for the primary prevention of obstetric anal sphincter injuries to reduce the risk of long-term accidental bowel leakage after childbirth.

Jorge JM, Wexner SD. Etiology and management of fecal incontinence. Dis Colon Rectum 1993;36:77–97.
Nilsson IEK, Åkervall S, Molin M, Milsom I, Gyhagen M. Symptoms of fecal incontinence two decades after no, one, or two obstetrical anal sphincter injuries. Am J Obstet Gynecol. 2021;224:276.e1-276.e23.

Continence 12S (2024) 101648
DOI: 10.1016/j.cont.2024.101648