The use of intrapartum ultrasound in operative vaginal birth: a retrospective cohort study

BACKGROUND: Poor outcomes from operative vaginal birth have been associated with failure to recognize malposition, breakdown in interdisciplinary communication, and deviation from accepted guidelines. We recently implemented a safety bundle including routine intrapartum ultrasound and a structured time-out and procedural checklist aiming to reduce maternal and perinatal morbidity from operative vaginal birth. OBJECTIVE: This study aimed to compare births where intrapartum ultrasound was used and those where it was not used during a safety bundle implementation period at Monash Health. STUDY DESIGN: We performed a retrospective cohort study at Monash Health during the transitional phase of implementing an operative vaginal birth safety bundle. We studied all women with operative vaginal birth and fully dilated cesarean delivery with a singleton cephalic term fetus. We compared births for which intrapartum ultrasound was used and those for which it was not. The primary outcome was neonates delivered in an unexpected position. Neonatal and maternal morbidity were also assessed, including a neonatal composite of Apgar score <7 at 5 minutes, cord lactate >8 mmol/L, need for resuscitation, significant birth trauma, or neonatal intensive care unit admission. To control for confounding by indication, we estimated propensity scores for the probability of using intrapartum ultrasound for each case based on maternal and labor characteristics, and adjusted the effect estimates for the propensity scores using multivariable logistic regression models. RESULTS: From August 2022 to July 2023, there were 1205 operative vaginal births or fully dilated cesarean deliveries at Monash Health, including 743 (61.7%) forceps, 346 (28.7%) vacuum, and 116 (9.6%) fully dilated cesarean deliveries. Over this time, we observed increased uptake of intrapartum ultrasound from 26% in August 2022 to 60% (P<.001) in July 2023, of the time-out from 21% to 58% (P<.001), and the checklist from 33% to 80% (P<.001) of operative second-stage births. Among the births where intrapartum ultrasound was used (n=509), compared with those where it was not (n=696), there were significantly more forceps births (67% vs 58%; adjusted odds ratio, 1.35; 95% confidence interval, 1.05–1.74; P=.021) and a reduction in vacuum births (24% vs 32%; adjusted odds ratio, 0.77; 95% confidence interval, 0.58–1.01; P=.059). There were no significant differences in fully dilated cesarean delivery or maternal morbidity. Intrapartum ultrasound use was associated with significantly fewer infants being delivered in an unexpected position (0.2% vs 2.2%; adjusted odds ratio, 0.08; 95% confidence interval, 0.00–0.44; P=.019) and a significant reduction in composite neonatal morbidity (22% vs 25%; adjusted odds ratio, 0.73; 95% confidence interval, 0.54–0.97; P=.031). CONCLUSION: During the implementation of a safety bundle, the use of ultrasound before operative vaginal birth was associated with fewer infants delivered in an unexpected position and reduced neonatal morbidity.