Episiotomy to prevent obstetric anal sphincter injury

Obstetric injury of the anal sphincter (OASI) is a serious consequence of vaginal childbirth. Women with OASI have an increased risk for anal incontinence in later life. In this thesis, we identified subgroups of women at a higher risk for OASI and analysed the association of a mediolateral episiotomy (MLE) and OASI. For all analyses, we used population-based data from the national Dutch Perinatal Registry. In chapter 2 we showed that a MLE with an anticipated birth weight more than 4000 grams and duration of the 2nd stage of labour of more than 60 minutes should be considered in nulliparous women. In chapter 3 our study group concluded that in both primiparous and multiparous women undergoing vaginal instrumental delivery, the use of a mediolateral episiotomy is associated with a greatly reduced risk of OASIS. In chapter 4, we demonstrated that the rate of OASI was higher in women who had OASI in their first delivery compared with women who had an uncomplicated first delivery and the rate is reduced with the use of a MLE. In chapter 5 we studied women with a VBAC and showed they have a significantly higher rate of OASI in comparison with women with a vaginal first delivery, with the exception of women with a VBAC after emergency CS for fetal distress. In chapter 6 a prediction model for OASI was developed and validated for women with spontaneous vaginal birth and women with operative vaginal delivery. These models can form a basis for counselling about the risk of OASI.