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ORIGINAL RESEARCH |
From the School of Health Sciences and the School of Medical Practice and Population Health, University of Newcastle, Newcastle, New South Wales, Australia.
Address reprint requests to: Pauline Chiarelli, PhD, Discipline of Physiotherapy, Box 24 Hunter Building, University of Newcastle, University Drive, Callaghan 2308, Australia; E-mail: Pauline.Chiarelli{at}newcastle.edu.au.
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ABSTRACT |
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 ABSTRACT MATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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METHODS: 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.
RESULTS: 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.
CONCLUSION: The present findings suggest that older and multiparous women, and women with joint hypermobility are at increased risk of postpartum anal incontinence symptoms after a high-risk delivery. Concurrent urinary incontinence, flow-stopping inability, and constipation are also associated with postpartum anal incontinence symptoms after high-risk deliveries.
Fecal incontinence, which has substantial negative impacts on quality of life,1 has been linked to mechanical sphincter disruption and nerve damage sustained during childbirth.2,3 In particular, forceps delivery,3–7 episiotomy,3,8 large fetal head size,9 and high fetal birth weight3,10 have been shown to increase the risk of damage to the anal sphincter. Urinary incontinence can similarly result from nerve damage sustained during childbirth9 and is therefore often associated with fecal incontinence.11 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.12,13
Although the first vaginal delivery is said to be responsible for most of the mechanical damage to the anal sphincter,14,15 subsequent births are associated with cumulative pudendal nerve damage16,17 and subsequent deterioration in fecal incontinence symptoms.15 As such, rates of fecal incontinence are reportedly higher among multiparous than primiparous women.12 Likewise, fecal incontinence becomes more prevalent with increasing maternal age.2,10
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 muscles18 and correlates with digital measures of pelvic floor muscle strength.19 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%.6 Lower rates of 2%10 and 5%12 have been reported for primiparous women, whereas higher rates of 19% have been reported for multiparous women.12 Not surprisingly, a substantially higher rate of 41% was found for women who sustained a third-degree tear during childbirth.3 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,3,12 whereas others do not.6 Some report fecal incontinence and flatal incontinence separately.10 Moreover, some studies do not clearly report definitions applied.15
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).
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MATERIALS AND METHODS |
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The study was conducted within the postpartum wards of three hospitals in the Hunter Region, New South Wales, Australia. The hospitals were a 580-bed metropolitan public teaching hospital with 3208 births a year, a 68-bed metropolitan private hospital with 962 births a year, and a 170-bed rural, public hospital with 1150 births a year. Data were collected between August 1998 and February 2000. The sample size was calculated on estimates from previous studies of fecal incontinence of 2% to 19%. A sample size of 550 women (which was the sample size calculated for the randomized trial in which the present data were collected) allows a 95% confidence interval (95% CI) of ±1.82% for a prevalence of 5%.
Women were eligible to join the study if they had a forceps or ventouse (vacuum)–assisted deliveries and/or delivery of a high birth weight infant. Eligible women were approached on the ward by one of three physiotherapists, usually within 48 hours of delivery. Consenting women completed a structured interview that measured sociodemographic characteristics and experiences of fecal incontinence after their recent delivery.
Participants were interviewed by telephone 12 months after their recruitment onto the study. The interview measured experiences of fecal incontinence of both solid and liquid stools, as well as precursors to fecal incontinence (flatal incontinence, soiling, and fecal urgency). Other relevant indicators, including constipation and urinary incontinence, were also assessed.
The major end point for the study was fecal incontinence at 12 months postpartum, measured as a dichotomous variable. Women were classified as having fecal incontinence if they responded "once a month or less," "once a week or less," "most days," or "every day" to either of the following items at the 12-month follow-up survey: Do you ever: (1) accidentally pass solid bowel motions into your underwear? (2) accidentally pass liquid bowel motions into your underwear? These questions have been validated against clinical opinions and a diary card.21
The secondary end point to the study was the experience of a precursor to fecal incontinence at 12 months postpartum, measured as a dichotomous variable. Women were classified has having a precursor to fecal incontinence if they reported experiences of either flatal incontinence, soiling, and/or fecal urgency. Flatal incontinence was measured as "the inability to hold wind when you really want to," with frequency coded as either "never," "once per month," or "more than monthly." Soiling was measured as "noticing soiling from the back passage on underwear" and was coded as either "none" or "minor or major." Fecal urgency was measured as "the inability to put off going to the toilet for 15 minutes" and was coded as either "yes" or "no."
Several associated risk factors were also measured, including age, body mass index, experiences of urinary incontinence before, during, and after pregnancy, urinary continence status at 12 months postpartum, perineal trauma during delivery, joint hypermobility, and abdominal striae as indicators of collagen status, type of delivery, experiences of postpartum constipation, flow-stopping ability at 12 months postpartum, and parity. Measurement of these characteristics is detailed elsewhere.20
Descriptive statistics, including proportions and 95% CIs, were calculated for self-reporting of fecal incontinence and its precursors, separately for primiparous and multiparous women. The 
2 statistic with risk estimates was used to identify statistically significant associations between parity and incontinence and its precursors. For the entire sample combined, separate multivariable logistic regression analyses were undertaken to identify factors significantly and independently associated with fecal incontinence and with precursor symptoms. Women who were pregnant at 12 months postpartum were excluded from the analyses. The statistical significance level was set at P < .05.
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RESULTS |
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There were no statistically significant differences between the overall mean age and parity of the women in the study and those who were missed, who transferred out, or who were not approached. Although the differences in mean age (3 years) and mean parity (0.4 births) between the private and public hospitals were statistically significant, they were not considered to be of clinical significance. Women were seen on average 2.06 days postpartum (range, 0 to 10 days). Most women were seen 1 day postpartum. Only one woman was seen at 10 days postpartum.
In total, 720 women were interviewed at baseline. At the 12-month follow-up interview, 99 women (13.7%) had dropped out of the study. Women who had become pregnant in the 12 months since the trial was initiated (n = 52) were excluded from the analyses. Fecal incontinence data were missing for one woman. A total of 568 women were included in the present study.
Table 1
shows the demographic characteristics and parity of women in the 12-month follow-up sample. Compared with Australian Perinatal Statistics,22 except for parity and education, the sample characteristics were very similar to the national norms. Compared with the national statistics, our sample had more primiparous women (52.5% versus 39.7%) and fewer women with four or more births (4.9% versus 9.9%).
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shows the prevalence of fecal incontinence and its precursors among all postpartum women, and separately for primiparous and multiparous women. Compared with primiparous women, multiparous women had significantly greater odds of soiling (odds ratio [OR] 2.18; 95% CI 1.26, 3.78; P = .005), of fecal urgency (OR 1.88; 95% CI 1.17, 3.01; P = .008), and for having any precursor (OR 1.82; 95% CI 1.28, 2.60; P = .001). For each of these indicators; the odds were nearly double for multiparous women compared with primiparous women.
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sets out the results of the logistic regression analysis undertaken to identify factors associated with fecal incontinence, of either solid or liquid stools. Fecal incontinence at 12 months postpartum was significantly associated with urinary incontinence at 12 months post-partum, being over 35 years of age, having joint hypermobility, and having experienced constipation in the postpartum.
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sets out the results of the logistic regression analysis to identify factors associated with the presence of precursors to fecal incontinence (namely flatal incontinence, soiling, and/or fecal urgency). The presence of precursor symptoms at 12 months postpartum was significantly associated with being unable to stop urine flow at 12 months, with having urinary incontinence at 12 months, with having experienced constipation in the postpartum period, and with being multiparous.
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DISCUSSION |
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Unlike earlier studies that have demonstrated marked differences in the prevalence rates for primiparous and multiparous women,12 the proportion of frank fecal incontinence in the present study was not statistically different for the two groups. This was the case for both solid and liquid stool incontinence, and for precursor flatal incontinence symptoms. Given that Sultan et al12 included all three symptoms in their definition of anal incontinence, it is unlikely that definitional differences account for this disparity. Instead, the results suggest that the protective effect of primiparity might be reduced among women who have undergone high-risk deliveries.
Not surprisingly, the prevalence of each of the three precursors to fecal incontinence was somewhat higher than for symptoms of frank incontinence. Specifically, the prevalence rates were 24.4% for flatal incontinence, 14.8% for fecal urgency, and 10.9% for soiling on underwear. In the Swedish study of primiparous women, a similar 26% reported symptoms of flatal incontinence at 9 months postpartum.10 A higher rate of 41% flatal incontinence has been shown for women who sustain a third-degree tear during childbirth, and a lower rate of 6% for those who do not.3 For fecal urgency, rates of 26% and 7%, respectively, were reported for these two groups.3 Thus, for both flatal incontinence and fecal urgency, the prevalence rates demonstrated for high-risk women in the present study are between the two extremes reported by Sultan et al.3 Although MacArthur et al23 reported relatively low rates of around 4% fecal urgency and 1% soiling at 10 months postpartum for a sample of UK women, their focus on new symptoms makes comparison difficult.
Four factors were significantly associated with fecal incontinence among this sample of high-risk women: having concurrent urinary incontinence, being aged over 35, having joint hypermobility, and having experienced periods of constipation in the postpartum. Two of these same factors—concurrent urinary incontinence and constipation—were also associated with the presence of precursor symptoms.
It is not surprising that both urinary incontinence and constipation were associated with fecal incontinence and its precursors. Like fecal incontinence, urinary incontinence can be the result of nerve damage sustained during childbirth.9 Likewise, constipation has been shown to result from damage to the pelvic floor muscles and their innervation sustained during childbirth,9 and it is commonly considered a risk factor for subsequent fecal incontinence. Indeed, urinary incontinence and constipation have been shown to be interrelated.24 Repeated straining at the stool is thought to exacerbate the perineal damage, resulting in weakness of the pelvic floor, perineal descent during straining, and secondary anatomic changes that result in anorectal dysfunction and further difficulty in defecation.25,26 These factors further increase the risk of subsequent fecal incontinence.12,13 Encouragement with pelvic floor exercises, which have been shown to improve pelvic floor muscle integrity,27 might be beneficial for women with these symptoms.
Similarly, the association with age is consistent with previous research. Studies by both Zetterstrom et al10 and MacArthur et al6 demonstrated that older maternal age is associated with higher rates of fecal incontinence. Even in the community generally, both US28 and Australian studies29–31 have demonstrated that the prevalence of fecal incontinence increases with age.
Joint hypermobility and flow-stopping inability were associated with fecal incontinence and precursor symptoms, respectively. This provides support for the hypothesis that fecal incontinence is associated with loss of pelvic floor muscles integrity. Indeed, although few previous studies have explored their association with fecal incontinence, the present findings suggest that hypermobility and flow-stopping inability might represent two useful indicators of fecal incontinence risk. In particular, hypermobility represents a trait characteristic that can be assessed during pregnancy, thereby enabling opportunities for monitoring for high-risk women.
Although we found no difference in fecal incontinence rates for primiparous and multiparous women, multiparity was associated with the presence of precursor symptoms. Most notably, rates of soiling and fecal urgency were higher among multiparous women. Sultan et al12 similarly demonstrated higher rates of precursors (flatal incontinence and fecal urgency) among multiparous women. As discussed earlier, though, the effect of primiparity was less pronounced in the present sample.
Three factors that have been linked to fecal incontinence in previous studies were not significant in the present study. Specifically, forceps delivery,3–6,10 episiotomy,8 and major anal sphincter tearing3,10 have all been shown to increase the risk of fecal incontinence. In the present study, neither instrumental delivery (either forceps or ventouse extraction) nor perineal trauma (defined as either episiotomy or sutured tearing) was associated with fecal incontinence or its precursors. This might again be explained by the inclusion of only high-risk women in the present study. Moreover, the combining of forceps and ventouse deliveries might have masked the risks of forceps delivery, because some studies have suggested that the use of ventouse is associated with significantly less tearing,3 sphincter defects,12 and subsequent fecal incontinence6 than the use of forceps. However, other studies suggest that both interventions increase fecal incontinence risk23—hence the approach taken in the present study. Finally, occult anal sphincter damage was not measured in the present study. Instead, because of the practical difficulties associated with clinical examination for a large sample of women, episiotomy and/or suturing were used as indicators of perineal trauma.
There are three other potential limitations to this study, two of which have been noted previously.20 First, the study response rate indicates that only 54.3% of women eligible for the study participated at baseline. To some extent, this limits the generalizability of the present study findings. Second, because the sample was drawn from only three hospitals, the external validity of the study might have been compromised. Importantly, though, the three hospitals served diverse population groups: urban public, urban private, and rural. Finally, the study relies on retrospective reports of anal incontinence symptoms over 12 months, which might be subject to recall bias. However, this was minimized through the use of validated questionnaire items.
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Footnotes |
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Received May 19, 2003. Received in revised form August 19, 2003. Accepted August 21, 2003.
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REFERENCES |
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2. Swash M. Faecal incontinence. BMJ 1993;307:636–7.
3. Sultan AH, Kamm MA, Hudson CN, Bartram CI. Third degree obstetric anal sphincter tears: Risk factors and outcome of primary repair. BMJ 1994;308:887–91.
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7. Donnelly VS, Fynes M, Campbell D, Johnson H, O’Connell PR, O’Herlihy C. Obstetric events leading to anal sphincter damage. Obstet Gynecol 1998;92:955–61.[Abstract]
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19. Sampselle C, DeLancey J. The urine stream interruption test and pelvic floormuscle function. Nurs Res 1992;42:73–7.
20. Chiarelli P, Cockburn J. Promoting urinary continence in postpartum women: A randomised controlled trial. BMJ 2002;324:1241–3.
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31. Lam T, Kennedy M, Chen F, Lubowski DZ, Talley NJ. Prevalence of faecal incontinence: Obstetric and constipation risk factors—A population based study. Int J Colorect Dis 1999;1:197–203.
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