Risk of obstetric anal sphincter injury with fundal pressure in second stage of labor: Transperineal ultrasound study

Aims Clinical management of the second stage of labor and effectiveness of preventive measures for severe perineal tears are controversial. The aim of this study was to evaluate the effect of using uterine fundal pressure during the second stage of delivery on obstetric anal sphincter injury (OASI), among primiparous women using three-dimensional (3D) transperineal ultrasonography. Methods A total of 73 women who had their first vaginal birth were included in the study, the fundal pressure group included women where the fundal pressure maneuver was applied (n = 37); and the control group included women who delivered spontaneously without fundal pressure (n = 36). Tomographic ultrasound imaging with 3D transperineal assessment was performed within 48 h of delivery, internal anal sphincter (IAS) and external anal sphincter (EAS) defect were determined. Results Five (13.5%) women in the fundal pressure group, seven (20%) women in the control group had complete EAS defect (p = 0.4). Complete IAS defect was observed in one (2.7%) woman in the fundal pressure group and two (5.7%) women in the control group (p = 0.5). A Half-moon sign was observed in one woman in both groups (p = 0.9). The rate of other signs was similar in both groups. Multivariate regression models revealed that none of age, fetal birth weight, episiotomy, length of the second stage of labor, fundal pressure application status, and number were independent predictors of complete IAS or EAS defect. Conclusion Fundal pressure with mediolateral episiotomy during the second stage of delivery does not increase the rate of OASI detected with ultrasonography.