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

Background Poor outcomes from operative vaginal birth (OVB) 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 (IPUS), a structured time-out and procedural checklist, aiming to reduce maternal and perinatal morbidity from OVB. Objectives To compare births where IPUS was and was not used during the 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 OVB safety bundle. We studied all women with OVB and fully-dilated cesarean (FDCS) births with a singleton cephalic term fetus. We compared births when IPUS was and was not used. 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 >8mmol/L, need for resuscitation, significant birth trauma or neonatal intensive care unit admission. To control confounding by indication, we estimated propensity scores (PS) for the probability of using IPUS for each case based on maternal and labor characteristics, and adjusted the effect estimates for the PS using multivariable logistic regression models. Results From August 2022 to July 2023 there were 1205 OVB or FDCS at Monash Health, including 743 (61.7%) forceps, 346 (28.7%) vacuum, and 116 (9.6%) FDCS births. Over this time, we observed increased uptake of IPUS from 26% in August 2022 to 60% (p < 0.001) in July 2023, of the time-out from 21% to 58% (p <0.001) and the checklist from 33% to 80% (p <0.001). of operative second stage births. Of births where IPUS was used (n = 509) compared to not used (n = 696), there were significantly more forceps births (67% vs. 58%, adjusted OR [aOR] 1.35, 95% CI 1.05 to 1.74, p = 0.021) and a reduction in vacuum births (24% vs. 32%, aOR 0.77, 95% CI 0.58 to 1.01, p = 0.059).There were no significant differences in FDCS or maternal morbidity. IPUS use was associated with significantly fewer infants being delivered in an unexpected position (0.2% vs. 2.2%, aOR 0.08, 95% CI 0.00 to 0.44, p = 0.019) and a significant reduction in composite neonatal morbidity (22% vs. 25%, aOR 0.73, 95% CI 0.54 to 0.97, p = 0.031). Conclusions During the implementation of a safety bundle, the use of ultrasound prior to OVB was associated with fewer infants delivered in an unexpected position and reduced neonatal morbidity.