Nitroglycerin for intraoperative uterus relaxation in cesarean section. Results of a randomized clinical study

Between June 1994 and July 1996, a prospective, randomized, double-blind clinical study was carried out on 97 patients scheduled for elective cesarean section under general anesthesia at the gynecology departments of the Virchow and Charité Hospitals (both university hospitals of the Humboldt University, Berlin) in order to test the efficacy of glycerol nitrate (GTN: syn.: nitroglycerin) as an intraoperative short-acting tocolytic agent to ease fetal extraction in cesarean section in comparison to a placebo. At the time of the uterine puncture incision, either 0.25 mg (n = 32 patients) or 0.5 mg (n = 34) of GTN or physiological saline (n = 31) was administered as an intravenous bolus. Maternal and fetal pulse rates and blood pressures were closely monitored. The authors developed a scale to evaluate the degree of decrease in uterine tone and the ease of fetal extraction. The statistical evaluation of these estimations revealed no significant easing of fetal extraction and no significant increase in the reduction of uterine tone after administration of both GTN dosages in comparison to the administration of placebo (p > 0.01). Easing of fetal extraction cannot be achieved with the administration of 0.25 or 0.5 mg GTN, at least not in elective cesarean sections of greater than 34 weeks of gestation.