When to stop? A single center experience on vacuum-assisted deliveries

To evaluate the association between vacuum-assisted vaginal delivery (VAVD) duration and procedural failure and neonatal morbidity, including major neonatal birth trauma, and to assess independent predictors of failed VAVD.

Retrospective cohort study of singleton, vertex pregnancies undergoing a trial of VAVD at a single center. VAVD duration was defined as time from first traction to delivery (successful VAVD) or to the decision to abandon the attempt (failed VAVD). Neonatal morbidity included Apgar scores and arterial pH, and major birth trauma outcomes were extracted from neonatal records. Multivariable logistic regression was performed to identify independent predictors of failed VAVD.

Among 2,355 VAVD attempts, 39 (1.7%) failed and all were delivered by cesarean. Failed VAVD had substantially higher cup detachment rates (61.5% vs 9%, p < 0.001) and longer duration (median 12 vs 4 min, p < 0.001). Neonatal outcomes were worse in failed VAVD, including higher rates of low 1-minute Apgar, low 5-minute Apgar, low arterial pH, and composite neonatal morbidity. Major birth trauma extraction identified higher subgaleal hematoma rates in failed VAVD, while intracranial bleeding was not documented. In time-dependent analyses, success declined from 98.3% at commencement to 61.5% at 20 min, whereas composite neonatal morbidity increased from 12.2% to 57.7%. In multivariable analysis, cup detachment, induction of labor, lower head station, and longer duration independently predicted failure.

Prolonged VAVD is associated with lower success and higher neonatal morbidity. Duration should inform dynamic reassessment alongside event-based stopping criteria, particularly cup detachments.