Effects of Prophylactic Oxytocin on Bleeding Outcomes in Women Undergoing Dilation and Evacuation: A Randomized Controlled Trial.

Objective: To estimate whether routine use of intravenous oxytocin decreases the frequency of interventions to control excess blood loss during dilation and evacuation (D&E).

Methods: In this multisite, randomized, double-blind, placebo-controlled trial, women undergoing D&E at 18-24 weeks of gestation received 30 units of oxytocin in 500 mL of intravenous fluid or 500 mL of intravenous fluid alone initiated on speculum placement. The primary outcome was the frequency of interventions to control excess bleeding. A sample size of 75 patients per group was needed to detect a 15% decrease in intervention from 20% to 5% with 80% power and two-sided alpha 0.05. Secondary outcomes included measured blood loss, complications, procedure duration, postoperative pain, and patient satisfaction.

Results: From November 2014 to February 2018, we screened 337 women and randomized 160 to receive prophylactic oxytocin (n=82) or placebo (n=78). Demographic characteristics were similar between groups. The frequency of interventions for bleeding, our primary outcome, was 7.3% in the oxytocin group vs 16.7% in the placebo group, difference of 9.4% (95% CI -21.0% to 1.9%). Interventions primarily included uterine massage and uterotonic administration. Among our secondary outcomes, median measured blood loss was lower in the oxytocin group at 152 (interquartile range 98-235) mL vs 317 (interquartile range 168-464) mL (95% CI 71.6-181.5). Frequency of hemorrhage, defined as blood loss of 500 mL or more and 1,000 mL or more, was lower in the oxytocin group at 3.7% vs 21.8%, difference of 18% (95% CI -29 to -6.9%) and 1.2% vs 10.3%, difference of 9.0% (95% CI -17 to -0.7%), respectively. Procedures were shorter in the oxytocin group at a median of 11.0 (interquartile range 8.0-14.0) vs 13.5 (interquartile range 10.0-19.0) minutes in the placebo group (95% CI 1.0-4.0). We found no differences in the frequency of nonhemorrhage complications, pain scores, or satisfaction scores between groups.

Conclusion: Prophylactic use of oxytocin during D&E at 18-24 weeks of gestation did not decrease the frequency of interventions to control bleeding. However, oxytocin did decrease blood loss and frequency of hemorrhage.

Clinical Trial Registration: ClinicalTrials.gov, www.clinicaltrials.gov, NCT02083809.