Episiotomy - Risk or protective factor for severe perineal trauma during vaginal delivery?

Purpose: Is an episiotomy a protective or a risk factor for severe perineal lacerations; which other obstetric influencing factors exist? Patients and Methods: Retrospective analysis of the perinatal data from Berlin from 1993 to 1999. Study inclusion criteria: vaginal delivery in singleton pregnancies. Setting up of two study subgroups: vaginal delivery of singletons, cephalic presentation > 34/0 gestational weeks, birth weight 2500 to 4000 g. Separate analysis of the primi- (subgroup 1) and multiparae (subgroup 2). Multivariate analysis with stepwise logistic regression. Identification of factors which correlate with severe perineal lacerations. Results: 74.7% of all vaginal deliveries of singletons (n = 128745) fulfilled the inclusion criteria. In spontaneous deliveries, the frequency of episiotomy was 60.8%, in vacuum extraction and forceps delivery 95.3 and 98.6% respectively. Severe perineal lacerations were significantly more frequent in vaginal-operative deliveries than in spontaneous vaginal delivery. If no episiotomy was incised, perineal lacerations stage 3/4 were less frequent in spontaneous and vacuum extraction deliveries. Following regression analysis, severe perineal lacerations were less frequent in primipara if the active period of labour is < 10 minutes, if no episiotomy is incised, in vacuum than in forceps extraction, if fetal head circumference is < 36 cm, and if no further traumas of the birth canal occur. Results were similar for multiparae: severe perineal lacerations were less frequent if the active period of labour is! 10 minutes, if no episiotomy is incised, and if no vaginal operative delivery occurs. Conclusions: Episiotomies seem to carry one of the highest risks for a severe perineal laceration among the avoidable risk factors. Therefore, use of an episiotomy must be restricted to well-justified cases. When considering perineal protection, vacuum extraction should be preferred to forceps extraction.