Lateral episiotomy protects primiparous but not multiparous women from obstetric anal sphincter rupture.

Kuopio University Hospital, Kuopio, Finland.
Acta Obstetricia Et Gynecologica Scandinavica (Impact Factor: 1.99). 10/2009; 88(12):1365-72. DOI: 10.3109/00016340903295626
Source: PubMed

ABSTRACT To identify the risk factors for obstetric anal sphincter rupture (OASR).
Retrospective population-based register study.
A total of 514,741 women with singleton pregnancy and vaginal delivery between 1997 and 2007 in Finland.
Primiparous (n = 2,315) and multiparous women (n = 534) with OASR were compared with primiparous and multiparous women without OASR by using stepwise logistic regression analysis.
The OASR risk.
Episiotomy decreased the likelihood of OASR for the primiparous [odds ratio (OR) 0.83, 95% CI (confidence interval) 0.75-0.92], but not the multiparous women (OR 2.01, 95% CI 1.67-2.44). The strongest risk factors for OASR among the primiparous women were forceps delivery (OR 10.20, 95% CI 3.60-28.90), birth weight over 4,000 g (OR 4.66, 95% CI 3.86-5.63), vacuum assisted delivery (OR 3.88, 95% CI 3.25-4.63), occiput posterior presentation (OR 3.17, 95% CI 1.64-6.15), and prolonged active second stage of birth (OR 2.06, 95% CI 1.65-2.58). Episiotomy was associated with decreased risks for OASR in vacuum assisted deliveries (OR 0.70, 95% CI 0.57-0.85). Risk factors for OASR among the multiparous women included forceps delivery (OR 10.13, 95% CI 2.46-41.81), prolonged active second stage of the birth (OR 7.18, 95% CI 4.32-11.91), birth weight over 4,000 g (OR 5.84, 95% CI 3.40-10.02), and vacuum assisted delivery (OR 4.17, 95% CI 3.17-5.48).
The results support the restrictive use of episiotomy, since 909 episiotomies appear to be needed to prevent one OASR among primiparous women. Equivalent estimate in vacuum assisted deliveries among primiparous women was 66, favoring routine use of episiotomy in such cases.

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    • "However, no difference in severe vaginal or perineal tears has been demonstrated when comparing restrictive and routine episiotomy policies [1]. We have previously reported that episiotomy is associated with a lower OASR rate in first births and a higher rate in second and subsequent births [2]. "
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    ABSTRACT: To assess the impact of hospital episiotomy policy on obstetric and anal sphincter rupture (OASR, n = 2448) rates and risks among singleton vaginal deliveries in Finland between 1997 and 2007. An observational, retrospective, population-based register study. All 424,297 women in hospitals with more than 1000 deliveries annually, were divided into three groups based on the episiotomy rate quartiles for 11 years and separated on the basis of whether the women were primiparous or multiparous. The lowest and the highest quartiles were compared against the hospitals with intermediate episiotomy rates, comprising the two quartiles around the median. Stepwise logistic regression analysis was used to adjust significant risk factors. The annual range of episiotomy varied from 11 to 94% in primiparous women, and from 1 to 46% in multiparous women. After adjustment the risk of OASR appears to be 39% lower (OR 0.61, 95% CI 0.52-0.90) in primiparous and 45% lower (OR 0.55, 95% CI 0.42-0.72) in multiparous women delivered in the highest quartile hospitals. At an individual level, episiotomy was a protective factor (OR 0.82, 95% CI 0.75-0.91) in primiparous women, but increased the risk by 2.36-fold in multiparous women (OR 2.36, 95% CI 1.86-2.84). The results suggest that high episiotomy rate provided protection from OASR among both groups of women. Among the multiparous women, the 2.4-fold risk of OASR related to episiotomy at an individual level might be explained by confounding by indication, since episiotomy was performed more often to women at a high risk of OASR.
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    ABSTRACT: Obstetric anal sphincter rupture (OASR) is a serious complication of delivery, which frequently results in faecal incontinence despite primary repair and has serious implications for women's health. The objective of this study was to assess whether human factors, workload and staffing at night, at weekends and during holidays has an effect on the increasing OASR rates among all singleton vaginal deliveries (n = 514,741) having occurred between 1997 and 2007 in Finland. Women (n = 2,849) with OASR were compared in terms of possible risk factors to women without OASR using stepwise logistic regression analysis. In Finland, the increase in OASR rate is striking, from 0.2% in 1997 to 0.9% in 2007. OASR rates varied from 0.49% to 0.58% (</= 0.001) according to the time of day, and were lowest at night. After adjustment for patient-mix and the use of interventions, the risk of OASR was 11% lower (95% CI 3-18%) at night and 15% lower (95% CI 3-26%) in July - the main holiday month. Only 14% of the increased OASR risk during the day time (8-23.59) was attributable to vacuum assistance and birth weight, whereas the holiday period had no effect. Decreased OASR rates at night and in July suggest that human factors such as decreased alertness due to fatigue or hospitals' administrative factors such as workload and staffing did not increase the rates of OASR.
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