The Use of Intrapartum Ultrasound before Instrumental Delivery in Real Life - Transition from Opt-In to Opt-Out Protocol.

BACKGROUND

Intrapartum ultrasound (IPUS) before instrumental delivery has not improved adverse neonatal outcomes in randomized trials, but only non-emergent indications were included. Whether real-life use of IPUS reduces birth trauma, such as cephalohematoma and subgaleal haemorrhage (SGH), remains unknown.

OBJECTIVE

To assess whether changing from an opt-in to an opt-out IPUS protocol affects IPUS uptake, the incidence of cephalohematoma, SGH and adverse maternal outcomes, and secondary outcomes including the rates of direct second-stage Caesarean delivery, failed, and sequential instrumental delivery.

STUDY

DESIGN

Retrospective cohort study of women who underwent attempted instrumental delivery in a Hong Kong public hospital. Outcomes were compared between opt-in (2020-2022) and opt-out (2023-2025) periods.

RESULTS

Among 822 attempted instrumental deliveries, IPUS uptake increased from 53.3% to 61.8% (P = 0.014). Cephalohematoma (11.1% vs. 12.3%), SGH (2.0% vs. 1.9%) and maternal adverse outcomes did not differ significantly between two periods. A trend towards a decreased rate of direct second-stage Caesarean section was observed (0.25% vs. 0.14%, P = 0.115). The second-stage Caesarean delivery to assisted vaginal birth ratio decreased from 0.056 to 0.031 (P = 0.093), suggesting that instrumental delivery was not discouraged by increasing IPUS use.

CONCLUSION

An opt-out protocol significantly increased IPUS uptake before instrumental delivery without increasing direct second-stage Caesarean section, but did not reduce cephalohematoma, SGH or maternal adverse outcomes. Given the rarity of severe neonatal trauma, demonstrating improved outcomes likely requires much larger sample size with a triage algorithm incorporating IPUS parameters to guide decision making for trial of instrumental delivery versus second-stage Caesarean section.