Comparison of two oxytocin regimens to prevent uterine atony at cesarean delivery: A randomized controlled trial

OBJECTIVE: To determine if high-dose oxytocin reduces the need for addition al uterotonic agents at cesarean. METHODS: A randomized, double-masked trial of two oxytocin regimens was per formed to prevent postpartum uterine atony in laboring women. The pharmacy prepared sequentially numbered oxytocin solutions containing either 10 U/50 0 mL or 80 U/500 mL of lactated Ringer's solution infused over 30 minutes a fter cord clamping. The need for additional uterotonic agents was determine d by the surgical team. Hypotension was diagnosed and treated with crystall oid or a pressor agent. To detect a 50% decrease in the need for additional uterotonic agents and considering a beta error of 0.2, 220 patients would be required in each group (alpha = 0.05, two-tailed chi (2) test). RESULTS: The low-dose group (n = 163) received 333 mU/min, and the high-dos e group (n = 158) received 2667 mU/min of oxytocin. The groups were similar with respect to risk factors for atony. Women in the low-dose group receiv ed additional uterotonic medication significantly more often than those in the high-dose group (39% compared with 19%, P < .001, relative risk 2.1, 95 % confidence interval 1.4, 3.0). Moreover, more women in the low-dose group received methylergonovine, 15-methyl prostaglandin F-2 alpha or both (9% c ompared with 2%, relative risk 4.8, 95% confidence interval 1.4, 16) after additional oxytocin (median 20 U) had been added to the study solution. The incidence of hypotension was similar in both groups. CONCLUSION: Compared with an infusion rate of 333 mU/min, oxytocin infused at 2667 mU/min for the first 30 minutes postpartum reduces the need for add itional uterotonic agents at cesarean delivery. (C) 2001 by the American Co llege of Obstetricians and Gynecologists.