[Efficacy of low-dose oxytocin during elective cesarean section]

In cesarean section, the optimal dose of oxytocin to reduce the risk of hemorrhage with the least risk of adverse effects has yet to be defined. We studied the effects of using 2 different doses of oxytocin in women undergoing elective cesarean section under spinal anesthesia. The women had had no prior labor.

Randomized multicenter trial enrolling 104 patients classified as ASA 1. Following fetal extraction and coinciding with umbilical cord clamping, a group of 52 women received 1 IU of oxytocin followed by an infusion of 2.5 IU x h(-1); a second group of 52 women received a continuous infusion of 20 IU at a rate of 700 mlU x min(-1) followed by 10 IU x min(-1). We compared uterine contractility (assessed as absent, moderate, satisfactory), postoperative vaginal bleeding (absent, light, moderate, heavy), hemodynamics, and adverse effects after administration of oxytocin and fetal extraction (electrocardiographic abnormalities, nausea, vomiting, discomfort, headache, blushing, trembling, chills, or chest pain).

No significant between-group differences in patient, obstetric, or anesthetic variables were detected. Uterine contraction was satisfactory in over 90% of the patients in both groups on initial assessment during surgery. After surgery, vaginal bleeding was absent or light in over 90% of the women. No significant differences in adverse events were detected between groups.

The incidence of obstetric bleeding is not higher when a lower dose of oxytocin is used; the rate of postoperative adverse events also does not increase.