To investigate the prevalence of and factors associated with fecal incontinence and its precursors among high-risk women at 12 months postpartum.

A survey of women in the immediate and later postpartum was conducted. Participants were 568 women at higher risk of anal sphincter damage, namely those who had an instrumental delivery and/or delivered a high birth weight infant (4000 g or more) at tertiary teaching hospitals in Australia. Women participated in a baseline hospital-based interview and a 12-month follow-up telephone interview. The main outcome measures were frank fecal incontinence (solid and/or liquid stool) and precursor symptoms (flatal incontinence, soiling, and/or fecal urgency) at 12 months postpartum.

Prevalence rates were 2.6% for solid stool incontinence and 4.9% for liquid stool incontinence. Overall, 6.9% women had either one or both of these symptoms of frank fecal incontinence. Prevalence rates were 24.4% for flatal incontinence, 10.9% for soiling, and 14.8% for fecal urgency. Overall, 32.4% women had at least one of these precurser symptoms. Concurrent urinary incontinence and postpartum constipation were significantly associated with both frank fecal incontinence and precursor symptoms. In addition, joint hypermobility and older maternal age were associated with frank fecal incontinence, whereas inability to stop the urine flow and multiparity was associated with precursor symptoms.

Fecal incontinence, which has substantial negative impacts on quality of life, has been linked to mechanical sphincter disruption and nerve damage sustained during childbirth. In particular, forceps delivery, episiotomy large fetal head size, and high fetal birth weight have been shown to increase the risk of damage to the anal sphincter. Urinary incontinence can similarly result from nerve damage sustained during childbirth and is therefore often associated with fecal incontinence. Complaints of constipation and straining to void in the period after delivery have also been shown to be associated with an increased risk of subsequent fecal incontinence.

Although the first vaginal delivery is said to be responsible for most of the mechanical damage to the anal sphincter, subsequent births are associated with cumulative pudendal nerve damage and subsequent deterioration in fecal incontinence symptoms. As such, rates of fecal incontinence are reportedly higher among multiparous than primiparous women. Likewise, fecal incontinence becomes more prevalent with increasing maternal age.

Two physiologic indicators are hypothesized to be related to fecal continence: effective pelvic floor muscle contraction, and pelvic organ support. Voluntary interruption of urine flow is commonly used as a test of neurofunctional integrity of the urethral sphincter muscles and correlates with digital measures of pelvic floor muscle strength. Likewise, joint hypermobility is widely accepted as a good indicator of poor collagen status and therefore pelvic organ and pelvic floor muscle integrity.

Estimates of the prevalence of fecal incontinence vary depending on the sample studied and the definitions applied. In a large international study of 7879 women, the reported prevalence of fecal incontinence at 3 months postpartum was 9.6%. Lower rates of 2% and 5% have been reported for primiparous women, whereas higher rates of 19% have been reported for multiparous women. Not surprisingly, a substantially higher rate of 41% was found for women who sustained a third-degree tear during childbirth. However, comparison of these rates is limited as a result of definitional differences: For example, some studies define anal incontinence to include symptoms of flatal incontinence, whereas others do not. Some report fecal incontinence and flatal incontinence separately. Moreover, some studies do not clearly report definitions applied.

The present study reports on the prevalence of and factors associated with fecal incontinence and its precursors among women at 12 months postpartum. To address definitional shortcomings of previous studies, prevalence rates were calculated separately for each of the indicators of fecal incontinence and its precursors, namely solid stool incontinence, liquid stool incontinence, flatal incontinence, soiling, and fecal urgency. In light of previously demonstrated associations between parity and fecal incontinence, prevalence rates were calculated separately for primiparous and multiparous women. The study is confined to women at higher risk of anal sphincter damage, namely those who had an instrumental delivery and/or delivered a high birth weight infant (4000 g or more).