The aim of this study was to assess the prevalence and risk factors of anal incontinence in an unselected pregnant population at second trimester. A survey of pregnant women attending a routine ultrasound examination was conducted in a university hospital in Oslo, Norway. A questionnaire consisting of 105 items concerning anal incontinence (including St. Mark’s score), urinary incontinence, medication use, and comorbidity was posted to women when invited to the ultrasound examination.
Anal incontinence is a bothersome ailment associated with many health complaints and discomfort in daily life: hygienic problems, limitations in occupational and social life, sexual dysfunction, reduced quality of life, and altered self-esteem. Anal incontinence (AI) is defined as involuntary loss of flatus or feces [
Obstetric anal sphincter injury (OASIS) is one of the main causes for female AI reported in nonpregnant women. Additionally, multiple vaginal deliveries can increase the risk of AI regardless of anal sphincter injury [
Prevalence of anal incontinence among women differs largely (2–28%) in previous studies and differs between different study populations [
Few previous studies have assessed the prevalence of anal incontinence in a female population of fertile age, and few studies have included nulliparous women [
The aim of this study was therefore to assess the prevalence and risk factors for anal incontinence in an unselected female population across parity groups in second trimester of pregnancy.
This study is part of a comprehensive perineum research study, which was approved by the Regional Committee for Medical Research Ethics in South-Eastern Norway (ref. S-08810d/20941) and the Institutional Personal Data Officer.
This study was conducted as a survey of pregnant women attending free of charge routine ultrasound examination at second trimester, from September 2009 to August 2010, in a large university hospital in Oslo, Norway. The pregnant women attending the ultrasound screening in our hospital represent a nonselected population from the entire Oslo area. All pregnant women in Norway are offered a free of charge second trimester routine ultrasound examination in gestational week 18–20, and 98% attend. In our hospital, this routine ultrasound is performed by specially educated midwives at the fetal medicine unit. The hospital receives admission notes from the local general practitioners when the woman is pregnant in the first trimester. The invitation to participate in our study, the questionnaire, and the informed consent were included as a part of the invitation to the routine ultrasound appointment. Midwives performing the routine ultrasound examination reminded the women of the study and collected the questionnaire and the signed informed consent. From the 7256 women who were posted a questionnaire, 973 women were not found in our postpartum labor ward database: they did not achieve 18 weeks pregnancy (pregnancy loss), they did not deliver in our hospital, or they had moved out of Oslo area or Norway, resulting in 6283 women eligible for study participation. We received 2851 filled-out questionnaires from the participants. Four women returned two questionnaires (twice during the same pregnancy), and one woman returned the questionnaire shortly after the index delivery. Thus, five filled-out forms were excluded from the analyses and the study group consisted of 2846 (of 6283 invited) women, resulting in a response rate of 45%.
The questionnaire consisted of 105 questions concerning anal and urinary incontinence, general health condition, drug use, and worries concerning pregnancy and delivery. The major part of the questions was chosen from validated questionnaires such as Due and Ottesen [
Anal incontinence was identified by self-reported leakage of gas, loose, or solid stools, lack of ability to defer defecation for 15 minutes (fecal urgency), use of pads or plugs, and alteration of lifestyle described in St. Mark’s score. We defined anal incontinence as a St. Mark’s score 3 or above (of maximal score 24). Women with St. Mark’s score from 0 to 2 were analyzed as a control group (no or infrequent AI). Fecal incontinence was defined as self-reported leakage of loose or solid tools. Urinary incontinence was defined as self-reported symptoms of stress or urge urinary incontinence.
Parity was adjusted to history of cesarean delivery. Thus, women with cesarean delivery only (never having delivered vaginally before) were categorized as “vaginal primiparous.”
The data were analyzed by using PASW (Predictive Analytics SoftWare, SPSS Inc., version 19.0, Chicago, IL, USA). Continuous data were categorized and the independent variables are presented as frequencies. Univariate analysis was performed to identify significant risk factors for anal incontinence. Univariate analyses were performed by Chi-square test. A significance level of 5% was chosen in all analyses. Variables with
Prevalence of self-reported anal incontinence (defined as St. Mark’s score 3 or more) in the entire study group was 8.4% (238/2846). Most of the women (80.3%) reported complete anal continence (2268/2846) with St. Mark’s score 0, and 11.3% (322/2846) women reported infrequent AI with St. Mark’s score 1 or 2. Inability to control flatus was the most frequent complaint, reported by 18.0% (513/2846). Of these, 385 women reported episodes of flatus incontinence without fecal incontinence. Fecal incontinence was reported by 6.0% (171/2846) and fecal urgency by 3.2% (90/2846) of the women.
Urinary incontinence was reported by 19% (547/2846) of the women. Urinary incontinence (UI) was significantly associated with reported anal incontinence among all parity groups and 32.4% of the women with AI also reported UI (
The majority of the 2846 women had answered the questionnaire when they were in the second trimester (84%), 12.2% in the first trimester, and 1.2% in the third trimester.
Most of the participating women were nulliparous (63%) (1792/2846). The majority of the participating women were Norwegian (77.5%). Non-Western origin was reported by 13.5% of the women. Mean age of the participating women was 31 years. Mean height was 168 cm and mean weight was 66.7 kg. Mean BMI was 23.6, range 16.0–42.4. Smoking was infrequent; only 2% (57/2851) women reported that they smoked during this pregnancy (Table
Anal incontinence defined in St. Mark’s score in subgroups of women. Values are given in frequencies (numbers) or mean/median.
Nulliparous ( |
Parous ( |
|||
---|---|---|---|---|
St. Mark’s |
St. Mark’s |
St. Mark’s |
St. Mark’s | |
Number of women | 1653 | 139 | 824 | 90 |
Born in |
|
|
||
|
93.2 ( |
6.8 ( |
91.6 ( |
8.4 ( |
|
86.1 ( |
13.9 ( |
81.7 ( |
18.3 ( |
Household income, USD |
|
|
||
|
93.2 ( |
6.8 ( |
92.0 ( |
8.0 ( |
|
90.0 ( |
10.0 ( |
82.9 ( |
17.1 ( |
Marital status |
|
|
||
|
92.8 ( |
7.2 ( |
89.7 ( |
10.3 ( |
|
92.6 ( |
7.4 ( |
93.0 ( |
7.0 ( |
|
82.5 ( |
17.5 ( |
75 ( |
25 ( |
Maternal educational level |
|
|
||
|
93.1 ( |
7.7 ( |
93.2 ( |
6.8 ( |
|
93.2 ( |
6.8 ( |
90.5 ( |
9.5 ( |
|
91.3 ( |
8.8 ( |
84.5 ( |
15.5 ( |
|
69.8 ( |
30.2 ( |
81.3 ( |
18.8 ( |
Working |
|
|
||
|
92.5 ( |
7.5 ( |
91.3 ( |
8.7 ( |
|
93.4 ( |
6.6 ( |
87.3 ( |
12.7 ( |
Maternal age mean/median (years) | 30.1/30.0 | 30.6/30.0 | 33.0/33.0 | 32.9/34.0 |
Maternal age |
|
|
||
|
92.8 ( |
7.2 ( |
90.3 ( |
9.7 ( |
|
89 ( |
11.0 ( |
89.9 ( |
10.1 ( |
BMI, mean | 23.6 | 23.8 | 23.6 | 24.7 |
BMI |
|
|
||
|
92.4 ( |
7.6 ( |
91.7 ( |
8.3 ( |
|
91.7 ( |
8.3 ( |
86.9 ( |
13.1 ( |
Smoking |
|
|
||
|
92.3 ( |
7.7 ( |
90.1 ( |
9.9 ( |
|
92.7 ( |
7.3 ( |
92.9 ( |
7.1 ( |
Pregnancy duration when answered |
|
|
||
|
88.4 ( |
11.6 ( |
93.9 ( |
6.1 ( |
|
92.5 ( |
7.5 ( |
89.7 ( |
10.3 ( |
Obstetrical history | ||||
OASIS |
|
|||
|
90.8 ( |
9.2 ( |
||
|
75.6 ( |
24.4 ( |
There was a significant difference in prevalence of AI among women with different obstetric histories. Prevalence of AI (defined as St. Mark’s score of 3 or above) increased with increasing vaginal parity (data not shown).
Of the nulliparous women, 7.8% (139/1792) reported anal incontinence. In the univariate analysis, non-Western background, low household income, being unmarried or single, low educational level, age 35 or more, answering the questionnaire in the first trimester (as opposed to second trimester), dermatological disease, ulcerative stomach disease, hypertension, rheumatoid arthritis, and muscle-skeletal complaints were significantly associated with anal incontinence among the nulliparous women (Tables
Risk of anal incontinence defined in St. Mark’s score 3–16 compared to women with St. Mark’s score 0–2. Crude OR and adjusted OR with confidence intervals. Adjusted OR is presented for significant variables only.
Nulliparous ( |
Parous ( |
|||
---|---|---|---|---|
Crude OR | Adj. OR (95% CI) | Crude OR | Adj. OR (95% CI) | |
Born in/maternal origin | ||||
|
1 | 1 | 1 | 1 |
|
2.21 (1.45–3.37) | 1.54 (0.85–2.78) | 2.44 (1.46–4.06) | 1.04 (0.44–2.46) |
Household income, NOK/USD | ||||
|
1 | 1 | 1 | 1 |
|
1.53 (1.02–2.30) | 1.07 (0.63–1.80) | 2.36 (1.36–4.08) | 1.40 (0.63–3.14) |
Marital status | ||||
|
1 | 1 | 1 | 1 |
|
1.04 (0.71–1.51) | 1.16 (0.76–1.77) | 0.65 (0.39–1.08) | 0.78 (0.46–1.36) |
|
2.74 (1.43–5.22) | 2.08 (0.91–4.74) | 2.89 (1.01–8.24) | 2.06 (0.54–7.89) |
Maternal educational level | ||||
|
1 | 1 | 1 | 1 |
|
0.99 (0.66–1.48) | 0.91 (0.60–1.40) | 1.45 (0.85–2.45) | 1.42 (0.81–2.49) |
|
1.30 (0.77–2.21) | 1.16 (0.65–2.09) | 2.52 (1.34–4.72) | 1.85 (0.86–3.99) |
|
5.89 (2.90–11.97) | 3.88 (1.46–10.32) | 3.17 (1.21–8.31) | 1.00 (0.21–4.03) |
Maternal age | ||||
|
1 | 1 | 1 | |
|
1.59 (1.03–2.47) | 1.62 (1.01–2.62) | 1.06 (0.67–1.65) | |
BMI | ||||
|
1 | 1 | 1 | |
|
1.10 (0.75–1.61) | 1.66 (1.05–2.61) | 1.36 (0.81–2.29) | |
Pregnancy duration when answered | ||||
|
1 | 1 | 1 | |
|
0.61 (0.38–0.99) | 0.53 (0.32–0.90) | 1.78 (0.84–3.77) | |
Illness/disease | ||||
Dermatological disease | ||||
|
1 | 1 | 1 | 1 |
|
1.97 (1.15–3.40) | 2.39 (1.36–4.20) | 2.85 (1.51–5.40) | 3.02 (1.51–6.02) |
Ulcerative stomach | ||||
|
1 | 1 | ||
|
2.60 (1.13–6.00) | 2.42 (0.95–6.15) | ||
Hypertension | ||||
|
1 | 1 | 1 | |
|
2.60 (1.13–6.00) | 2.05 (0.77–5.48) | 0 | |
Rheumatoid arthritis or other muscular-skeletal problems | ||||
|
1 | 1 | 1 | |
|
2.77 (1.36–5.62) | 2.45 (1.14–5.31) | 1.83 (0.74–4.51) | |
Kidney/urinary problems | ||||
|
1 | 1 | ||
|
1.36 (0.85–2.18) | 1.87 (0.94–3.72) | ||
Medication | ||||
Pain killers | ||||
|
1 | 1 | 1 | |
|
1–10 (0.50–2.43) | 2.40 (1.02–5.66) | 1.80 (0.62–5.20) | |
Obstetrical history | ||||
OASIS | ||||
|
1 | 1 | ||
|
3.20 (1.51–6.76) | 3.83 (1.68–8.73) | ||
Previous macrosomy, >4000 g | ||||
|
1 | |||
|
0.80 (0.42–1.51) | |||
Previous vacuum extraction | ||||
|
1 | |||
|
0.58 (0.29–1.15) | |||
Forceps | ||||
|
1 | |||
|
0.83 (0.19–3.58) |
In the multivariate analysis, low educational level, dermatological disease, and rheumatoid arthritis remained as significant factors for AI (Table
After excluding the 140 women with previous cesarean delivery only, the subgroup of vaginal parous women consisted of 914 women. Overall anal incontinence among parous women was 9.8% (90/914). In the group of women with one previous vaginal delivery, 8.5% (61/714) reported AI, whereas the group of women with more than one previous vaginal delivery, as many as 14.5% (29/200), reported AI (
Of the parous women, 15.9% had previously delivered at least one macrosomic (>4000 g) infant (145/914), 156 reported previous delivery with vacuum extraction, and 24 women reported a previous forceps delivery. An obstetric history with instrumental delivery or a macrosomic infant was not associated with AI. Previous delivery with OASIS was reported by 41 women (4.5%) and was strongly associated with AI.
In the univariate analysis, previous delivery with OASIS, non-Western background, low household income, being unmarried or single, low educational level, age 35 or more, BMI 25 or more, dermatological disease, and use of pain killers were significantly associated with anal incontinence among the parous women (Tables
In the multivariate analysis, previous delivery complicated with OASIS and dermatological disease remained as significant risk factors for AI (Table
The higher risk of AI associated with previous OASIS remained threefold in the more severe forms of AI, if defining AI as self-reported St. Mark’s score of 5 or above (12.2% and 3.8%) or if 7 or above (7.3% and 2.3%) instead of 3 or above (Table
Distribution of St. Mark’s score among parous women with OASIS and without OASIS.
Parous women without previous OASIS | Parous women with previous OASIS | |
---|---|---|
|
|
|
St. Mark’s 0 | 81.4 ( |
63.4 ( |
St. Mark’s 1-2 | 10.4 ( |
12.2 ( |
St. Mark’s 3–16 | 8.1 ( |
24.4 ( |
St. Mark’s 5–16 | 3.8 ( |
12.2 ( |
St. Mark’s 7–16 | 2.3 ( |
7.3 ( |
The subgroup of parous women with previous cesarean only (
Women who reported having a dermatological disease reported also more anal incontinence than women without this disease (Table
This population-based study showed that previous obstetric anal sphincter injury was the strongest risk factor for self-reported AI among pregnant parous women. Among the nulliparous women, a low educational level and comorbidity were associated with anal incontinence. The group of women with previous deliveries with cesarean section only had the lowest prevalence of AI, indicating that pregnancy per se may not represent a major risk factor for AI. These findings support the notion that the process of vaginal delivery may be more damaging to the anal continence mechanisms than pregnancy per se.
We found a surprisingly high frequency of self-reported AI among nulliparous women (7.8%). Low socioeconomic status (low income, low education) is a well-known reason for lower health status and increased morbidity, and previous studies show that self-rated health predicts morbidity well [
A previous OASIS was the strongest risk factor for self-reported anal incontinence in all analyses in parous women, with and without adjusting for other factors, and in all categories of severity of anal incontinence. In our study, women with previous OASIS reported a lower prevalence of AI than women in previous studies on nonpregnant women [
Many previous studies of AI describe only the frequency of the different components of AI. We chose to describe the prevalence of AI as a score, to be able to perform multivariable analyses of the assessed variables in our study. The reason to choose the St. Mark’s score 3 as cutoff for AI was to be able to compare the results from this study to our previous study [
Similarly to our previous study of nonpregnant women, urinary incontinence was reported by 19.2% of the participants [
Strength of this study is that the pregnant population was unselected and consisted of all parity groups, including nulliparous women. The majority of studies on female anal incontinence have assessed nonpregnant women 6–24 months after delivery.
Another strength of this study is that we also assessed comorbidity and medication use in addition to obstetrical history. To our knowledge, no previous studies have assessed anal incontinence and comorbidity among pregnant women. Among nulliparous women, comorbidity seems to have association to anal incontinence. Further research is needed to explore whether this is a consistent finding across population groups and to explore which mechanisms could underlie such an association.
A weakness in our study is that the response rate among the invited women was less than 50%, and this can cause self-selection bias among the study participants. Similar selection bias was observed in the Norwegian MoBa study, where higher educated women more likely agreed to participate [
Bias of women with a previous OASIS and complaints of AI having been more eager to participate in the study is unlikely, since the prevalence of AI in the subgroup of women with previous OASIS was lower (24.4%) than that in the previously reported studies (from Norway) [
All data in this study was based on self-reporting from the participants, and thus information of their obstetric history can include errors. It is likely that women remember correctly the number of previous deliveries, delivery mode, and infant birth weight, but not all women are aware of having suffered from OASIS [
We found an association between self-reported dermatological disease and self-reported AI for all parity groups, which has not been reported before. We can only speculate reasons for this association; women that have AI may also be more sensitive to dermatological bother than others, perhaps associated with the fecal incontinence with affection of perianal skin. Possibly, there could be a common tissue specific risk for both AI and dermatological conditions. Women who reported dermatological problems also reported more worries; another explanation could be that these women were in general more sensitive to different symptoms and signs. In a further study more detailed questions about the type of dermatological disease would be of interest when assessing comorbidity in relation to symptoms of AI.
We have performed a large number of analyses due to a large number of detailed information about obstetric history and maternal characteristics. The study population is relatively young, and thus, frequency of comorbidity and medication use was very low among the participants, which can give results by chance. Therefore, all analyses were also performed without comorbidity and medication use. This did not alter the conclusions; low educational level among nulliparous and OASIS among parous women were the most important factors associated to AI.
We conclude that among parous women, previous OASIS is the most important risk factor for anal incontinence and other obstetrical events only had a minor effect on development of AI. As OASIS is a modifiable risk factor, and frequency may rapidly be altered after introduction of obstetrical perineal support programs [
The authors are grateful for the assistance of the midwives and nurses at the fetal medicine unit at Oslo University Hospital, helping them collect the questionnaires from the women.