Anal sphincter tears: Prospective study of obstetric risk factors

Perinatal Center, Department of Obstetrics and Gynaecology, Sahlgrenska University Hospital/Ostra, Göteborg, Sweden.
BJOG An International Journal of Obstetrics & Gynaecology (Impact Factor: 3.45). 08/2000; 107(7):926-31. DOI: 10.1097/00006254-200101000-00007
Source: PubMed


To evaluate intrapartum risk factors for anal sphincter tear.
A prospective observational study.
Delivery unit at the University Hospital in Göteborg, Sweden.
2883 consecutive women delivered vaginally during the period between 1995 and 1997. Information was obtained, from patient records and from especially designed protocols which were completed during and after childbirth.
Anal sphincter (third and fourth degree) tear.
Anal sphincter tear occurred in 95 of 2883 women (3.3%). Univariate analysis demonstrated that the risk of anal sphincter tear was increased by nulliparity, high infant weight, lack of manual perineal protection, deficient visualisation of perineum, severe perineal oedema, long duration of delivery and especially protracted second phase and bear down, use of oxytocin, episiotomy, vacuum extraction and epidural anaesthesia. After analysis with stepwise logistic regression, reported as odds ratio, 95% confidence interval, the following factors remained independently associated with anal sphincter tear: slight perineal oedema (0.40, 0.26-0.64); manual perineal protection (0.49, 0.28-0.86); short duration of bear down (0.47, 0.24-0.91); no visualisation of perineum (2.77, 1.36-5.63); parity (0.59, 0.40-0.89); and high infant weight (2.02, 1.30-3.16). Analysis of variance showed that manual perineal protection had a stronger influence on lowering the frequency, and lack of visualisation of perineum and infant weight had a stronger influence on raising the frequency, of anal sphincter tears in nulliparous compared with parous women.
Perineal oedema, poor ocular surveillance of perineum, deficient perineal protection during delivery, protracted final phase of the second stage, parity and high infant weight all constitute independent risk factors for anal sphincter tear. Such information is essential in order to reduce perineal trauma during childbirth.

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    • "Among the affected professions there is an on-going discussion regarding the possible reasons for and the prevention of severe perineal trauma. Some obstetricians and midwives in Sweden argue that the increase in sphincter injuries is associated with midwives neglecting the importance of perineal protection and instead using hands-off techniques and the upright birth positions promoted by the natural birth movement of the 1990s [12, 13]. This view is supported mainly by observational studies [12, 13] but they may have had an impact on the accepted truth described by the midwives and contributed to their focus on the hands-on techniques. "
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    ABSTRACT: Background The occurrence of obstetric anal sphincter injuries (OASIS) has increased in most high-income countries during the past twenty years. The consequences of these injuries can be devastating for women and have an impact on their daily life and quality of health. The aim of this study was to obtain a deeper understanding of midwives’ lived experiences of attending a birth in which the woman gets an obstetric anal sphincter injury. Methods A qualitative study using phenomenological lifeworld research design. The data were collected through in-depth interviews with 13 midwives. Results The essential meaning of the phenomenon was expressed as a deadlock difficult to resolve between a perceived truth among midwives that a skilled midwife can prevent severe perineal trauma and at the same time a coexisting more complex belief. The more complex belief is that sphincter injuries cannot always be avoided. The midwives tried to cope with their feelings of guilt and wanted to find reasons why the injury occurred. A fear of being exposed and judged by others as severely as they judged themselves hindered the midwives from sharing their experience. Ultimately the midwives accepted that the injury had occurred and moved on without any definite answers. Conclusions Being caught between an accepted truth and a more complex belief evoked various emotions among the midwives. Feelings of guilt, shame and the midwife’s own suspicion that she is not being professionally competent were not always easy to share. This study shows the importance of creating a safe working environment in which midwives can reflect on and share their experiences to continue to develop professionally. Further research is needed to implement and evaluate the effect of reflective practices in relation to midwifery care and whether this could benefit women in childbirth.
    BMC Pregnancy and Childbirth 08/2014; 14(1):258. DOI:10.1186/1471-2393-14-258 · 2.19 Impact Factor
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    • "However the sensitivity remained low across both cohorts, indicating a low chance of a high-risk result indicating anal sphincter injury. At present the OASIs score is a reasonable predictor of anal sphincter injury, but may be improved by parameters not recorded in this dataset such as perineal body length [22,23,29]. "
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    ABSTRACT: Background Perineal trauma involving the anal sphincter is an important complication of vaginal delivery. Prediction of anal sphincter injuries may improve the prevention of anal sphincter injuries. Our aim was to construct a risk scoring model to assist in both prediction and prevention of Obstetric Anal Sphincter Injuries (OASIs). We carried out an analysis of factors involved with OASIs, and tested the constructed model on new patient data. Methods Data on all vaginal deliveries over a 5 year period (2004–2008) was obtained from the electronic maternity record system of one institution in the UK. All risk factors were analysed using logistic regression analysis. Odds ratios for independent variables were then used to construct a risk scoring algorithm. This algorithm was then tested on subsequent vaginal deliveries from the same institution to predict the incidence of OASIs. Results Data on 16,920 births were analysed. OASIs occurred in 616 (3.6%) of all vaginal deliveries between 2004 and 2008. Significant (p < 0.05) variables that increased the risk of OASIs on multivariate analysis were: African-Caribbean descent, water immersion in labour, water birth, ventouse delivery, forceps delivery. The following variables remained independently significant in decreasing the risk of OASIs: South Asian descent, vaginal multiparity, current smoker, home delivery. The subsequent odds ratios were then used to construct a risk-scoring algorithm that was tested on a separate cohort of patients, showing a sensitivity of 52.7% and specificity of 71.1%. Conclusions We have confirmed known risk factors previously associated with OASIs, namely parity, birth weight and use of instrumentation during delivery. We have also identified several previously unknown factors, namely smoking status, ethnicity and water immersion. This paper identifies a risk scoring system that fulfils the criteria of a reasonable predictor of the risk of OASIs. This supersedes current practice where no screening is implemented other than examination at the time of delivery by a single examiner. Further prospective studies are required to assess the clinical impact of this scoring system on the identification and prevention of third degree tears.
    BMC Research Notes 07/2014; 7(1):471. DOI:10.1186/1756-0500-7-471
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    • "A survey of female obstetric consultants in the UK, found 31% of obstetricians chose elective caesarean mainly for fear of anal sphincter injury (Al-Mufti et al., 1996). Between one-third and two-thirds of women who sustain a recognized third-degree tear during delivery suffer subsequent faecal incontinence (Sultan et al., 1994; Samuelsson et al., 2000; Andrews et al., 2006; Dudding et al., 2008). Obstetric anal sphincter injury has a significant impact on a women's physical and emotional health. "
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    ABSTRACT: This descriptive study explored the roles and responsibilities of expert midwives involved in teaching staff from midwifery students to senior consultants/physicians. We have earlier conducted an intervention project, aimed at decreasing the number of anal sphincter tears. During this intervention a local core team of expert midwives was established. These experts continued the training of colleagues after the midwife instructor had fulfilled the active training period. Eighteen expert midwives from the four Norwegian hospitals which took part in this training program were recruited. To explore the views and experiences of these expert midwives, a questionnaire was completed, and the results were analyzed qualitatively. Before starting the program 24% of the midwives, working at the delivery ward were negative towards the supervision and project, while 46% were positive. One year after the program's start 92% were positive. Negative feedback at the beginning of the intervention came mostly from the media and professional midwifery organizations. The expert midwives felt that doctors were the most challenging to teach. The response from pregnant women was ultimately positive. Eighteen well motivated midwives became highly appreciated experts after an intensive training program and deemed themselves better and more successful professionals than before.
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