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One versus two uterotonics: Which is better for minimizing postpartum blood loss?

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A Cochrane network meta-analysis concluded that the two highest-ranked interventions for reducing the rate of postpartum blood loss ≥ 500 mL were misoprostol plus oxytocin and ergonovine plus oxytocin. However, administering two agents significantly increases the rate of adverse effects.


 

References

Excessive postpartum bleeding is a major cause of maternal morbidity and mortality. Worldwide, obstetric hemorrhage is the most common cause of maternal death.1,2 Medications reported to reduce postpartum bleeding include oxytocin, misoprostol, ergonovine, methylergonovine, carboprost, and tranexamic acid. A recent Cochrane network meta-analysis of 196 trials, including 135,559 women, distilled in 1,361 pages of analysis, reported on the medications associated with the greatest reduction in postpartum bleeding.3 Surprisingly, for preventing blood loss ≥ 500 mL, misoprostol plus oxytocin and ergonovine plus oxytocin were the highest ranked interventions. This evidence is summarized here.

Misoprostol plus oxytocin

After newborn delivery, active management of the third stage of labor, including uterotonic administration, is strongly recommended because it will reduce postpartum blood loss, decreasing the rate of postpartum hemorrhage (PPH).4 Both oxytocin and misoprostol are effective uterotonics. However, the combination of oxytocin plus misoprostol appears to be more effective than oxytocin alone in reducing the frequency of postpartum blood loss greater than 500 mL.3 To understand the clinical efficacy and adverse effects (AEs) of combined oxytocin plus misoprostol a meta-analysis was performed for both vaginal and cesarean deliveries (CDs).

Efficacy and AEs during vaginal delivery. In the meta-analysis, about 6,000 vaginal deliveries were analyzed, with no significant differences for misoprostol plus oxytocin versus oxytocin alone found for the following outcomes: maternal death, intensive care unit admissions, and rate of blood loss ≥ 1,000 mL (1.7% for both uterotonics vs 2.2% for oxytocin alone).3 Misoprostol plus oxytocin was significantly superior to oxytocin alone for the following outcomes: reduced risk of blood transfusion (0.95% vs 2.5%), reduced risk of blood loss ≥ 500 mL (5.9% vs 8.0%), reduced risk of requiring an additional uterotonic (3.6% vs 5.8%), and a smaller decrease in hemoglobin concentration from pre- to postdelivery (-0.89 g/L).3

In my opinion, the difference in hemoglobin concentration, although statistically significant, is not of clinical significance. However, compared with oxytocin alone, misoprostol plus oxytocin caused significantly more nausea (2.4% vs 0.66%), vomiting (3.1% vs 0.86%), and fever (21% vs 3.9%).3 A weakness of this meta-analysis is that the trials used a wide range of misoprostol dosages (200 to 600 µg) and multiple routes of administration, including sublingual (under the tongue), buccal, and rectal. This makes it impossible to identify a best misoprostol dosage and administration route.

Efficacy and AEs during CD. In the same meta-analysis about 2,000 CDs were analyzed, with no significant difference for misoprostol plus oxytocin versus oxytocin alone for the following outcomes: maternal death, intensive care unit admissions, and PPH ≥ 1,000 mL blood loss (6.2% vs 6.5%).3 Misoprostol plus oxytocin was significantly superior to oxytocin alone for the following outcomes: reduced risk of blood transfusion (2.6% vs 5.4%), reduced risk of blood loss ≥ 500 mL (32% vs 47%), reduced risk of requiring an additional uterotonic (14% vs 28%), and a smaller decrease in hemoglobin concentration from before to after delivery (-4.0 g/L).3 In my opinion, the statistically significant difference in hemoglobin concentration is not clinically significant. However, compared with oxytocin alone, misoprostol plus oxytocin caused significantly more nausea (12% vs 6.1%), vomiting (8.1% vs 5.4%), shivering (13% vs 7%), and fever (7.7% vs 4.0%).3

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