Background & Objectives: Nitroglycerin is found to have vasodilatory effect. It has also a relaxing effect on the smooth muscles of other organs including uterus. This study investigates the effect of intravenous nitroglycerin in emergency cesarean sections in which rapid and transient uterine relaxation for rapid and nontraumatic extraction of the fetus is necessary.
Methods: Sixty pregnant women who were candidated for emergency cesarean and needed rapid uterine relaxation for different reasons were selected. These subjects underwent spinal anesthesia and at the time of uterine incision, 100 micrograms of nitroglycerin was injected to them intravenously. The time lapse between nitroglycerin administration and fetal extraction, the degree of uterine relaxation, the amount of intraoperative hemorrhage, uterine tone after fetal delivery and APGAR scores of the infants were all controlled and recorded. Also with regard to the vasodilatory effect of nitroglycerin and probably its resultant homodynamic problems, blood pressure, heart rate and arterial O2 saturation were recorded before and after nitroglycerin injection and throughout the surgery.
Results: The results showed that in 53 (88.3%) of the patients the uterus was acceptably relaxed and the fetus was delivered very easily. Only in 7 patients (11.7%) uterine relaxation was not acceptable. The mean decrease in systolic and diastolic blood pressures after nitroglycerin administration compared with before injection BP was 12.97 mmHg (12.210 %) and 7.86 mmHg (12.208 %), respectively. There was not seen any prolonged effect of the drug such as uterus relaxation tone or abnormal bleeding. Also, none of the delivered infants had low APGAR scores. Besides, in patients with acceptable uterine relaxation the first and fifth minute APGAR score of infants were higher (p = 0.008, p = 0.000).
Conclusion: This study shows that nitroglycerin can relax uterine smooth muscles very rapidly and transiently and in emergencies it can be an appropriate alternative to the other tocolytic agents with prolonged effect or onset time.