Incidence and risk factors for severe perineal laceration after vaginal delivery in Japanese patients

Objective: The aim of this study was to assess the frequency of severe perineal lacerations defined as either third- or fourth-degree lacerations during normal spontaneous vaginal delivery and to evaluate potential risk factors in Japanese patients. Materials and methods: An electronic audit of the perinatal database at the Tama-Nagayama Hospital of Nippon Medical School and Yamaguchi Hospital from 1997 through 2004 was completed. Singleton vaginal vertex deliveries were analyzed for potential risk factors using univariate and multivariate logistic regression analysis. Results: From the database, 7,946 deliveries were identified, with 135 deliveries resulting in severe lacerations (1.7%). In the multivariate logistic regression analysis, severe lacerations were associated significantly with primiparous (odds ratio, 4.36; 95% CI, 2.17–9.57), oxytocin use (odds ratio, 2.19; 95% CI, 1.27–3.73), midline episiotomy (odds ratio, 4.68; 95% CI, 2.09–11.55), forceps-assisted delivery (odds ratio, 7.11; 95% CI, 1.95–20.59), vacuum-assisted delivery (odds ratio, 5.93; 95% CI, 3.38–10.36), and shorter attendant experience (odds ratio, 2.88; 95% CI, 1.12–9.81). Conclusions: The present study demonstrated that operator factors, such as midline episiotomy, oxytocin use, assisted delivery and attendant experience, are independent risk for severe perineal lacerations after vaginal delivery in Japanese patients. The results suggest that midline episiotomy and assisted vaginal delivery, especially forceps-assisted delivery should be avoided in patients who are being delivered of a first child whenever possible.