Objectives: The aim of this study was to determine whether choice of obstetric instrument at operative vaginal delivery is associated with any differences in the rate of significant perineal trauma and whether this rate is modified by the use of episiotomy.
Study design: The occurrence of significant perineal trauma among 323 consecutive operative vaginal deliveries was evaluated according to type of instrument used and performance of episiotomy. These findings were compared with spontaneous vaginal deliveries during the same period.
Results: Among forceps deliveries the use of episiotomy was not associated with a difference in the occurrence of significant perineal trauma (55% vs 46%; relative risk, 1.2; 95% confidence interval, 0.8-1.9). Among vacuum extraction deliveries an increased rate of such trauma was noted when episiotomy was used (34.9% vs 9. 4%; relative risk, 3.7; 95% confidence interval, 1.2-11.2). There was no difference in the rate of significant perineal trauma according to type of forceps used. In a logistic regression analysis forceps delivery with or without episiotomy was associated with an increase of >10-fold in the rate of significant perineal trauma with respect to vacuum extraction deliveries without episiotomy.
Conclusions: Our data suggest that in forceps delivery neither the type of forceps nor episiotomy influences the risk of significant perineal trauma. When vacuum extraction delivery is performed, the use of episiotomy is associated with a higher risk of significant perineal trauma.