A randomised trial of carbetocin versus syntometrine in the management of the third stage of labour

OBJECTIVE: Syntometrine is an effective uterotonic agent used in preventing primary postpartum haemorrhage but has adverse effects including nausea, vomiting, hypertension and coronary artery spasm. Carbetocin is a newly developed long-acting oxytocin analogue that might be used as an uterotonic agent. We compare the efficacy and safety of intramuscular (IM) carbetocin with IM syntometrine in preventing primary postpartum haemorrhage. DESIGN: Prospective, double-blinded, randomised controlled trial. SETTING: Delivery suite of a university-based obstetrics unit. POPULATION: Women with singleton pregnancy achieving vaginal delivery after and throughout 34 weeks. METHODS: Three hundred and twenty-nine eligible women were randomised to receive either a single dose of 100 microgram IM carbetocin or 1 ml IM syntometrine (a mixture of 5 iu oxytocin and 0.5 mg ergometrine) at the end of second stage of labour. MAIN OUTCOME MEASURES: Difference in haemoglobin drop measured 2 days after delivery between the two groups. RESULTS: There was no difference in the drop of haemoglobin concentration within the first 48 hours between the two groups. The incidence of additional oxytocic injections, postpartum haemorrhage (blood loss ≥ 500 ml) and retained placenta were also similar. The use of carbetocin was associated with significant lower incidence of nausea (relative risk [RR] 0.18, 95% confidence interval [CI] 0.04–0.78), vomiting (RR 0.1, 95% CI 0.01–0.74), hypertension 30 minutes (0 versus 8 cases, P < 0.01) and 60 minutes (0 versus 6 cases, P < 0.05) after delivery but a higher incidence of maternal tachycardia (RR 1.68, 95% CI 1.03–3.57). CONCLUSIONS: IM carbetocin is as effective as IM syntometrine in preventing primary postpartum haemorrhage after vaginal delivery. It is less likely to induce hypertension and has a low incidence of adverse effect. It should be considered as a good alternative to conventional uterotonic agents used in managing the third stage of labour.