Uterine Electromyography for Estimation of Uterotonic Efficiency for Postpartum Hemorrhage Prevention

RATIONALE

Postpartum hemorrhage is the leading cause of maternal mortality worldwide. In the Western world the estimated risk of life threatening postpartum hemorrhage is 2 on 1000 births. Most frequently (up to 90% of cases of postpartum hemorrhage) it is a consequence of uterine atony or inappropriate uterine contraction. In clinical practice preventing postpartum hemorrhage is key and routinely, different prophylactic uterotonic drugs are used. The first-line recommended drug for postpartum hemorrhage prevention is oxytocin. However, a recent Cochrane meta-analysis concluded that the most effective drugs (compared to oxytocin) to prevent postpartum hemorrhage of 500 ml or more are ergometrine with oxytocin, misoprostol with oxytocin and carbetocin.

Carbetocin is a synthetic heat-stable analogue of oxytocin, with a longer half-life. It shares the same mechanism of action and the same side-effects as oxytocin. The recommended dose of carbetocin is 100 μg, which is equivalent to 10 μg (5 IU) of oxytocin. In the WHO carbetocin multicenter, double-blind, randomized trial, the intramuscular administration of 100 μg of heat-stable carbetocin was discovered to be noninferior to the administration of 10 IU of oxytocin for the prevention of postpartum hemorrhage after vaginal birth. Some studies have found carbetocin to be an effective prophylactic agent with a favourable side effect profile for the third stage of labour in caesarean sections, reducing the use of additional uterotonic agents, blood and recovery time. Moreover, carbetocin was found to be effective in reducing the need for additional uterotonic use and postpartum blood transfusion in women at increased risk of postpartum hemorrhage undergoing cesarean delivery. In one study, carbetocin was also found to be more effective than oxytocin in preventing postpartum hemorrhage in twin pregnancies delivered by cesarean section.

Uterine contractions in pregnancy, labour and postpartum can be detected using electromyography. Myometrial contractility can be objectively and non-invasively assessed in vivo by monitoring uterine electromyography (EMG), as uterine contractions are the result of the electrical activity generated and propagated in the myometrium.

To our knowledge, no study has reported oxytocin or carbetocin effects using postpartum electromyography.