Intrapartum ultrasound in the second-stage labor: a meta-analysis and evidence appraisal of clinical outcomes and safety

Background Accurate assessment of fetal head position and descent during the second stage of labor is essential for safe decision-making, but digital examination is subjective and operator-dependent. Intrapartum ultrasound has been proposed as an objective adjunct, yet its effect on clinical outcomes remains uncertain. Aim To evaluate the impact of intrapartum ultrasound on delivery mode, maternal outcomes, and neonatal outcomes. Methods A systematic review and meta-analysis was conducted according to PRISMA guidelines. Randomized controlled trials and cohort studies were identified through searches of PubMed, EMBASE, the Cochrane Library, and Web of Science from database inception to August 31, 2026. Pooled risk ratios, mean differences, and 95% confidence intervals were calculated. Subgroup and sensitivity analyses explored heterogeneity. Results Eight studies including 4,315 women were analyzed. Intrapartum ultrasound was not associated with significant differences in cesarean birth, spontaneous vaginal birth, vacuum-assisted birth, or neonatal outcomes. No statistically significant difference was observed in the duration of the second stage of labor (MD = −4.0 minutes, 95% CI = −15.6 to 7.5). Two outcomes showed statistically significant differences, with higher forceps-assisted birth (RR = 1.14, 95% CI = 1.05 to 1.24; 54.4% vs 47.7%) and a small increase in postpartum hemorrhage (RR = 1.11, 95% CI = 1.01 to 1.22; 25% vs 22.5%). Conclusion In the available evidence, intrapartum ultrasound in the second stage of labor shows limited clinical impact, with no clear effect on cesarean section or most maternal and neonatal outcomes. A small association with higher forceps use and postpartum hemorrhage was observed, but its clinical relevance remains uncertain and may reflect practice variation and outcome ascertainment differences. Further well-designed trials with standardized indications and outcome definitions are warranted to clarify whether intrapartum ultrasound can improve patient-important endpoints in specific clinical contexts.