Attempted and Successful Vacuum-Assisted Vaginal Delivery by Prepregnancy Body Mass Index
To assist decision on operative delivery, intrapartum transperineal ultrasonography is one tool that can be incorporated into clinical assessment. In nulliparous women, a progression angle of 120° or less, a downward or horizontal fetal head position, and a midline angle of 35° or greater on intrapartum transperineal ultrasonography predicts an 85% chance of difficult vacuum delivery requiring more than four pulls.2 Importantly, intrapartum transperineal ultrasonography is better-tolerated by laboring women than conventional digital vaginal assessments.3
Intrapartum transperineal ultrasonography has not been specifically applied to obese women requiring vacuum assistance. Nevertheless, this is certainly one direction worthy of pursuit in future research, not only to improve clinicians' confidence in identifying the right case for successful operative delivery among obese women, but to enhance patient safety and advance the art of operative deliveries.