Fecal incontinence, defined as recurring episodes of involuntary loss of stool or flatus (National Institutes of Health. Conference for Researchers in Female Pelvic Floor Disorders. NIH Terminology Workshop, December 13–14, 1999, Rockville, Maryland), is an embarrassing and psychosocially debilitating condition.1,2 The incidence of fecal incontinence in the general population is estimated to range from 2.2% to 7%.3–5 Fecal incontinence affects a much greater proportion of the elderly population, ranging from 15% to 47%.6–8 Obstetric delivery is thought to be the leading contributor to the development of fecal incontinence in women. However, the true incidence of fecal incontinence after childbirth is unknown.
This study was the first of several studies conducted through the Fecal Incontinence Postpartum Research Initiative funded by the National Institute of Child Health and Development (NICHD, R01 HD41139–04). The Fecal Incontinence Postpartum Research Initiative is a population-based study of all women who delivered a liveborn infant in the state of Oregon. The initiative aims to estimate the incidence of fecal incontinence in postpartum women, to identify factors in pregnancy and the postpartum period that predict development and resolution of fecal incontinence, and to identify modifiable risk factors that may enable the development of interventions to prevent fecal incontinence. This paper presents phase I data, which focuses on the incidence of fecal incontinence and describes the characteristics of women who suffer from postpartum fecal incontinence.
PARTICIPANTS AND METHODS
Figure 1 depicts studies within the Fecal Incontinence Postpartum Research Initiative. All women delivering a liveborn infant in the state of Oregon between April and September of 2002 were mailed a survey to assess the incidence of fecal incontinence within 3–6 months of delivery (phase I). Eligible women were identified through Oregon state birth certificates. Women having abortions, stillbirths, or adoptions, out of state residents, and women for whom identifiers were missing were not eligible for the study. Surveys contained unique identifiers rather than personal identifiers to maintain anonymity. Institutional review board approval was obtained from both Oregon Health & Science University (IRB 251 EXP) and the Department of Human Services, Health Services, Multnomah County (IRB-02–02). Informed consent was obtained from participants returning the surveys.
Eligible individuals were sent study materials, which included a cover letter, postcard, and fecal incontinence questionnaire in both English and Spanish. The sequence of correspondence was as follows: 1) initial mail questionnaire packet was sent, 2) a “tickler” was sent 7–10 days after the questionnaire packet as a reminder and thank you note, and 3) a second mail questionnaire packet was sent 7–14 days after the tickler to mothers who had not yet responded.
Women with symptoms of fecal incontinence were instructed to complete the enclosed two-page questionnaire. Women without any symptoms of fecal incontinence returned a postcard that indicated no symptoms to maximize the response rate of unaffected individuals.
Fecal Incontinence Postpartum Research Initiative questionnaires were based on two previously validated fecal incontinence survey instruments,9,10 and the modified survey was validated in a pilot study.11 The two-page survey included 30 items related to delivery events, fecal incontinence symptoms, and patient characteristics, including smoking history and age at most recent delivery. Questions regarding fecal incontinence used the following format: “Since delivery of this baby, have you experienced… (eg, an inability to control solid stool)?” The questionnaire was designed with Teleform format software (Cardiff Software, Vista, CA).
Data were analyzed with SAS 9.1 (SAS Institute, Cary, NC). The incidence of fecal incontinence was calculated as a percentage of all respondents who indicated an inability to control symptoms of fecal incontinence, ie, gas, diarrhea, and solid stool.
Descriptive statistics were used to explore the risk factors for severe fecal incontinence (defined as incontinence of solid or liquid stool). Baseline characteristics of women with and those without severe incontinence were compared by using t tests and Wilcoxon rank-sum for continuous variables and χ2 for categorical variables. Multiple logistic regression analyses based on the maximum likelihood method were performed to calculate the parity-adjusted odds ratio (OR) and 95% (CI) for likelihood of having severe fecal incontinence.
As shown in Figure 1, there were 23,377 births in Oregon from April 2002 through September 2002. During this 6-month period, 21,824 postal questionnaire packets were sent to eligible Oregon residents. A total of 8,774 women responded to our survey (40.2% response rate); 2,569 (29.3%) reported symptoms of fecal incontinence, and 6,205 (70.7%) reported no symptoms. Among women reporting symptoms of incontinence, 46% (1,172) reported symptom onset after their first child, 21.8% after their second, and 9.7% after their third.
Table 1 presents characteristics of women with fecal incontinence in our study compared with state statistics during the study period. Among women reporting fecal incontinence, the mean age at most recent delivery was 28.5 years (standard deviation 6.0). As shown, our study population was not that different from the population of women delivering in Oregon at the same time, with the exception that more women in our group reported having a primary cesarean (21.5% versus 14.6%), perhaps in part reflecting the higher proportion of women aged 30 years or older (44.1% versus 35.6%) in the study. Forty-one percent of women reporting fecal incontinence were primiparous, 34% had two deliveries, and 24.6% reported 3 or more deliveries (among whom, 8.9% had a parity of 4 or higher).
Nearly one third (2,569 of 8,774) of postpartum women reported experiencing incontinence of flatus or stool or both since the delivery of their most recent child. Women most commonly reported onset of fecal incontinence symptoms after delivery of their first or second child. If all nonrespondents were assumed not to have fecal incontinence, the lowest incidence of fecal incontinence in the postpartum period would be 11.8%.
Table 2 portrays the spectrum of fecal incontinence experienced by postpartum women. Almost half (46.4%) of the women reporting postpartum fecal incontinence were incontinent of stool, almost two thirds of whom reported incontinence of solid stool. More than one third (38.1%) of women reported problems controlling flatus only. Of the positive respondents, 730 women had trouble controlling solid stool (either solid stool only or combined with flatus, diarrhea, or incontinence to all three). Almost 5% of women reported fecal incontinence exclusively with intercourse.
Frequency of incontinence ranged from daily to exclusively during intercourse. One in five women (20%) who were incontinent of solid stool reported involuntary loss of solid stool one to three times per week, 11% reported daily occurrences, and 59% reported occurrences less than once per week. Women reporting incontinence of flatus were evenly divided in frequency, with 31.3% reporting daily incontinence, 39.2% reporting occurrences 1–3 times per week, and 29.5% experiencing incontinence less than once per week. A minority of women (4.6%) reported incontinence of flatus or stool exclusively with intercourse.
Risk factors for severe fecal incontinence are shown in Table 3. Among the 2,569 women with fecal incontinence, their average age at first delivery was 25.3 years (±5.9), the average weight of this infant was 3,488.1 g (±551.4), with 50.8% reporting infant weight of 3,500 g or more, their heaviest infant weighed 3,600 g on average (±553.9), and their average pushing time was 54.7 minutes (±67.5). Twenty-four percent had ever had a cesarean delivery, 66% reported ever having a laceration or tear, 12.3% were current smokers, and 41.6% were primiparous. Descriptive analyses revealed that age at this birth, age at first birth, body mass index (BMI), pushing time, instrument-assisted delivery at this birth, laceration requiring repair at this or any birth, and smoking were associated with severe fecal incontinence symptoms.
To explore the associations of these measures with severity, we conducted a multiple logistic regression analysis. After adjusting for parity, BMI more than 30, length of pushing, forceps-assisted delivery, fourth-degree laceration, and current smoking were significantly associated with severe incontinence (incontinence of stool). Table 4 presents the odds ratios for each factor.
Recently, with increasing national interest in maternal requested cesarean, there is heightened interest about whether cesarean delivery may prevent incontinence and pelvic floor disorders later in life. A recent National Institutes of Health State-of-the-Science conference sponsored by the NICHD raised concerns regarding the current state of knowledge regarding route of delivery and fecal incontinence, stating that current studies lacked power and matched controls to assess the degree of association (Fenner D. Anal Incontinence. Paper presented at NIH State-of-the-Science Conference: Cesarean Delivery on Maternal Request, March 27–29, 2006, Bethesda, Maryland). Before recommending cesarean delivery as a method for reducing the likelihood of incontinence, it is critical to have more accurate data.12
Data from this large population-based study indicate that more than one in four postpartum women suffer from fecal incontinence. This incidence (29.3%) falls within the upper range of previously reported rates for postpartum women.11,13–20 Fecal incontinence has been previously reported to occur in 3–26% of women having a vaginal delivery.21,22 At 3 months postpartum, Eason et al21 found only 3% of women reporting incontinence of stool, whereas 26% reported incontinence of flatus. Our higher incidence may be attributed to the inclusion of symptoms of flatus incontinence in our postal questionnaire, as in Pollack et al’s20 similar survey of Swedish mothers with a 25% incidence of incontinence. Our methodology and population differ from many of these studies in the following important ways: we aimed to evaluate postpartum fecal incontinence a priori (which differs from Hannah et al23 who evaluated fecal incontinence among their population of women randomized to route of delivery for breech presentation and Eason et al21 who evaluated fecal incontinence among women in a randomized trial of perineal massage); we evaluated symptoms proximate to delivery rather than examining the association among women reporting fecal incontinence later in life,24 making the association between event and symptoms more direct; and our study was population-based rather than limited to specific populations such as primiparas,14,20,22,25 clinics,15 or hospitals.17 The methods (survey of entire cohort of women delivering in a state) and size of this study make it likely that these data accurately reflect the incidence of fecal incontinence in the general population of postpartum women. These data reflect immediate symptomatology, however, so they may not be an accurate reflection of long-term fecal incontinence. Other phases of this project are aimed to address this important additional question. Although incontinence of flatus may be regarded as the most common and least severe of incontinence symptoms, it may still pose embarrassing social and hygienic problems for many women. Thus, it is an important facet of overall fecal incontinence incidence. Because only 20% of those affected by fecal incontinence consult their clinician for help,1 this study suggests that providers may want to inquire about incontinence of flatus or stool during routine postpartum visits.
There have been conflicting reports about whether fecal incontinence is caused by pregnancy or childbirth. Many reports indicate a direct link between childbirth, particularly vaginal delivery, and fecal incontinence through either disruption of the anal sphincter or pudendal nerve injury or both.17,26–29 Others, however, find that fecal incontinence occurs even in women who delivered by cesarean.23,25 Although, in this particular phase, we were not able to report antenatal characteristics of women without fecal incontinence since women without symptoms returned a postcard with limited data, we were able to examine what factors were more likely to be associated with severe fecal incontinence. Among women reporting fecal incontinence, forceps-assisted vaginal delivery and third- or fourth-degree laceration were associated with more severe disease. Similarly, longer pushing time, smoking, and obesity were also associated with more severe symptoms. Similar to findings of Lal et al,25 we did not find, however, that cesarean was protective against severe fecal incontinence, because one in five women with severe fecal incontinence had a cesarean delivery. Our study adds to the growing evidence that cesarean delivery is not completely protective against severe fecal incontinence.21,24,30,31
This study is not without limitations. The survey methodology used in many previous studies and ours does rely upon maternal recall of events. Studies have shown that the accuracy of maternal recall depends on the question asked (with factors such as route of delivery, requiring stitches, and birth weight being most reliable),32–34 the characteristics of the population (eg, education level, ethnicity, age at first birth, and parity),32,34–36 and timing.37 Questioning shortly after delivery allows for a more direct evaluation of the impact of route of delivery and true incidence of symptoms. Data from our pilot study comparing self-report with medical records revealed that our population was reliable for many of the factors listed: 100% accuracy for report of any laceration and route of delivery including assisted vaginal deliveries, 88% for tears into the sphincter, and 95.8% for birth weight within 5% of actual weight. However, recall on total time pushing was more variable, with one third reporting pushing time within 10 minutes of what was posted in the medical record.11 Fornell et al38 found good reproducibility for self-reported fecal incontinence up to 10 years.
Our unique approach, ie, having women without symptoms return a prepaid postcard with minimal additional effort, increased our response rate in the group that is least motivated to return the survey. This same approach, however, limited our ability to compare women with and those without symptoms. However, future phases of the study specifically allow for detailed comparisons as well as longitudinal follow-up.
Because women are increasingly living longer, focus on important quality-of-life issues, such as incontinence and factors that may reduce its likelihood, increases. This paper presents data from one of the largest studies conducted focusing on postpartum incontinence. These data suggest that fecal incontinence is common in postpartum women, with more than one in four reporting symptoms of fecal incontinence within the first 6 months of delivery. Higher BMI, longer pushing, forceps-assisted delivery, third- or fourth-degree laceration, and smoking were associated with severe fecal incontinence. The association between weight (BMI) and fecal incontinence is documented in nonobstetric populations30,39 but is new for obstetric patients. Studies in nonobstetric patients have found an association between BMI and increased intra-abdominal pressure, suggesting that this increased pressure may place a stress on normal continence mechanisms.40,41 Further studies may be warranted to investigate whether this is the mechanism for the association in pregnancy as well. We did not find that cesarean delivery was completely protective of severe incontinence because one in five women with severe incontinence experienced a cesarean delivery. Given the high prevalence and high burden of this condition, clinicians should consider adding questions about fecal incontinence in their postpartum check-ups. Similarly, these data suggest that there may be a benefit to extending postpartum visits beyond 6–8 weeks to enable surveillance of incontinence symptoms. Further evidence is needed regarding the natural history of postpartum symptoms, risk factors for progression, and possible preventive strategies.
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