The safety and efficacy of intravenous (IV) oxytocin are similar to that of intramuscular (IM) oxytocin, according to a recent study published in SAGE Open Medicine.
Takeaways
- The study found that both intravenous (IV) and intramuscular (IM) administration of oxytocin demonstrated similar safety and efficacy profiles in reducing the risk of postpartum hemorrhage (PPH), a common complication of labor.
- Oxytocin is the most recommended uterotonic drug for preventing PPH and is included in active management of the third stage of labor (AMTSL). While both IV and IM routes are recommended by the World Health Organization, evidence suggests potential advantages of IV administration.
- The study was a double-blind, randomized, controlled trial involving pregnant women with specific criteria, such as singleton normotensive pregnancy and successful vaginal delivery, to compare the effectiveness of IV versus IM oxytocin administration.
- The primary outcome measured was postpartum blood loss, with secondary outcomes including maternal hematocrit levels, vital signs, and adverse effects of oxytocin administration.
- While both administration routes showed similar outcomes in terms of safety and efficacy, the study indicated a higher likelihood of needing additional uterotonics for primary PPH risk among patients receiving IV oxytocin. This suggests that IM administration may be the preferred route of administration in preventing primary PPH.
Postpartum hemorrhage (PPH), the most common complication of the third stage of labor, is often caused by uterine atony, tissue trauma, and retained placenta. Uterine atony has been linked to 75% to 90% of PPH cases, and active management of the third stage of labor (AMTSL) is recommended to reduce uterine atonic primary PPH risk.
Oxytocin administration is included in AMTSL and is the most recommended uterotonic drug. While the World Health Organization recommends either IV or IM administration of oxytocin, the organization has stated evidence indicates improved PPH outcomes from IV utilization. However, few studies have compared these administration routes.
To compare the safety and efficacy of IV and IM oxytocin for reducing PPH risk, investigators conducted a double-blind, randomized, controlled study. Participants included pregnant women aged 18 years or older with singleton normotensive pregnancy, no observed PPH risk factor, and successful vaginal delivery.
Exclusion criteria included grand-multiparity, preterm gestation, prior uterine surgery or cesarean section, multiple pregnancy, fetal macrosomia, contraindication to vaginal delivery, prior PPH history, polyhydramnios, medical illness, induction of labor, febrile illness, anemia, hypertension, tachycardia, coagulation disorders, antepartum hemorrhage, and uterine fibroids.
Participants were randomized 1:1 to receive IV or IM oxytocin. Hematocrit levels were confirmed from blood samples collected after recruitment. Patients in the IM group also received IV inactive placebo, while those in the IV group received IM inactive placebo.
Oxytocin was administered as 10 IU contained in either IV or IM alongside 1 ml of water for placebo. Following administration, maternal pulse rate and blood pressure were assessed every 5 minutes for 30 minutes, then every 15 minutes for 90 minutes. Postpartum blood loss (PPBL) was measured as the primary outcome of the analysis.
There were 115 in the IV group and 117 in the IM group included in the final analysis. Similar demographic and obstetric characteristics were reported between the 2 groups, and participants were more often multiparous. The mean gestational age in the IV and IM groups were 279.9 ± 54.89 and 278.0 ± 54.72 days, respectively.
Mean PPBL did not significantly differ between groups, at 254.17 ± 34.85 ml in the IV group and 249.4 ± 39.88 in the IM group. The proportion of women with significant PPH also did not significantly differ between groups, at 14.8% and 10.3%, respectively.
The mean percentage of prepartum hematocrit was 34.32 ± 3.43% in the IV group and 35.30 ± 3.37% in the IM group. For postpartum hematocrit, these rates were 31.92 ± 2.57% and 33.2 ± 2.21%, respectively. Mean hematocrit changes did not significantly differ between groups.
Additionally, maternal pulse, temperature, and systolic and diastolic blood pressure did not differ between the 2 groups, nor did adverse maternal effects of oxytocin including nausea, vomiting, shivering, headache, tachycardia, and pyrexia. However, more participants in the IV group needed additional uterotonics for primary PPH than the IM group, at 21.73% and 14.53%, respectively.
These results indicated similar safety and efficacy profiles between IV and IM administration of oxytocin, but increased likelihood of needing additional uterotonics to reduce primary PPH risk among patients receiving IV. Investigators concluded IM may be the preferred role of administration.
Reference
Okaforcha EI, Eleje GU, Ikechebelu JI, et al. Intravenous versus intramuscular oxytocin injection for preventing uterine atonic primary postpartum haemorrhage in third stage of labour: A double-blind randomised controlled trial. SAGE Open Med. 2024;12. doi:10.1177/20503121241230484
