– Use of ultrasound before operative vaginal delivery (OVD), especially head-perineum distance (HPD) measurement, has shown promising results in the prediction of vacuum-assisted delivery failure. However, the studies were monocentric and there was variation in reported thresholds.

To assess HPD measurement as a predictor of the failure of vacuum-assisted delivery, requiring an instrument change.

Multicenter, retrospective cohort study in three tertiary maternity hospitals in France, from January 2019 to December 2020. Analyses included all vacuum-assisted delivery attempts in singleton pregnancies of ≥ 34 weeks gestation and for which an ultrasound HPD measurement was available. Vacuum deliveries were classified as success or failure (i.e., leading to an instrument change).

- Among 23,974 deliveries, vacuum delivery was performed in 2,432 cases (10.1 %) among which 1,197 (49.2 %) had HPD measurements. Instrument change occurred in 123 (10.3 %). The area under the curve for predicting the failure of a vaginal delivery with vacuum according to HPD measurement was 0.58, smaller in the success group (40.1 ± 12.6 mm vs 43.3 ± 10.9 mm, p <0.001). After multivariable analysis, gestational age and HPD were significantly associated with OVD failure (respectively, OR(95 %CI) 1.26 (1.05-1.51), p=0.015, 1.14 (1.04–1.25), p=0.004); whereas fetal head position did not reach the significance level (p=0.06). However more failure were observed in case of transverse position compared to anterior position (ORa = 2.10 (1.13 to 3.90)).

- In our multicenter and retrospective study, HPD measurement has a low predictive value for the need for instrument change in vacuum-assisted OVD. It will be interesting to test mix models including maternal and sonographic parameters.

Ultrasound

Labor

Delivery

Birth

Vacuum

© 2025 The Authors. Published by Elsevier Masson SAS.