Intrapartum transperineal ultrasound used to predict cases of complicated operative (vacuum and forceps) deliveries in nulliparous women.

Introduction: The objective of this study was to investigate the predictive value of intrapartum transperineal ultrasound in the identification of complicated operative (vacuum or forceps) deliveries in nulliparous women.

Material And Methods: Prospective observational study of nulliparous women with an indication for operative delivery who underwent intrapartum transperineal ultrasound before fetal extraction. Managing obstetricians were blinded to the ultrasound data. Intrapartum transperineal ultrasound was performed immediately before blade application, both at rest and concurrently with contractions and active pushing. Operative delivery was classified as complicated when one or more of the following situations occurred: three or more tractions; a third-/fourth-degree perineal tear; significant bleeding during the episiotomy repair; major tear or significant traumatic neonatal lesion.

Results: A total of 143 nulliparous women were included in the study (82 vacuum-assisted deliveries and 61 forceps-assisted deliveries), with 20 fetuses in occiput posterior position. Forty-seven operative deliveries were classified as complicated deliveries (28 vacuum-assisted deliveries, 19 forceps-assisted deliveries). No differences in obstetric, intrapartum or neonatal characteristics were observed between the study groups, with the following exceptions: birthweight (3229 ± 482 uncomplicated deliveries vs. 3623 ± 406 complicated deliveries; p < 0.003) and number of vacuum tractions (1.4 uncomplicated deliveries, 4.5 complicated deliveries; p < 0.0005). The strongest predictors of a complicated delivery, using the area under the receiver-operating characteristics curve (AUC), were the angle of progression with active pushing (AoP2) (AUC 86.9%) and the progression distance with active pushing (PD2) (AUC 74.5%). The optimal cut-off value for predicting a difficult operative delivery was an AoP2 of 153.5° (sensitivity 95.2%; false-positive rate 5.9%) or PD2 of 58.5 mm (sensitivity 95.2%; false-positive rate 7.1%).

Conclusions: The sonographic parameters AoP2 and PD2 can be used to predict cases of complicated operative deliveries in nulliparous women.