Effect of Intraoperative Sublingual Nitroglycerin on the Rate of Active Uterine Segment Incision in Preterm Cesarean...

Active segment uterine incisions, including classical, T-shaped, and high transverse incisions, are often performed during preterm cesarean deliveries (CD), especially in patients delivering at less than 30 weeks of gestation, when the lower segment can have inadequate space for a safe maternal or fetal delivery. These uterine incisions increase the risk of maternal morbidity due to longer operative time, increased blood loss, and the rate of uterine dehiscence in future pregnancies compared to lower segment uterine incisions. Patients with uterine incisions in the active segment are also not candidates for future trials of labor. Nitroglycerin is known to cause uterine relaxation and has been used in cases of uterine inversion, manual removal of the placenta, difficult fetal extractions at cesarean delivery, and external or internal version for second twins. This study aimed to determine if intraoperative sublingual nitroglycerin is associated with a decreased active segment uterine incision rate in patients undergoing CD prior to 30 weeks of gestation. The outcomes included maternal blood loss, umbilical artery pH, and 1-min and 5-min Apgar scores.

In this retrospective case-control study, patients with singleton pregnancies between 22 weeks 0 days and 29 weeks six days of gestation undergoing CD at two community-based hospitals were compared between the years of 2017 and 2023. Maternal and neonatal variables were collected and analyzed using equality of means and Mann-Whitney U tests as appropriate.

Patients who received nitroglycerin (n=26) were compared with patients at the same week of gestation who did not receive nitroglycerin (n=26) during cesarean delivery. The rate of active segment uterine incision was lower in the group that received intraoperative nitroglycerin (26.9%) compared to the group that did not (61.5%; p=0.012). Quantitative blood loss (QBL) was significantly decreased in patients who received nitroglycerin, with a mean QBL of 583 mL compared with 944 mL in patients who did not (p=0.031). Neonatal outcomes, including umbilical artery pH and Apgar scores, were not significantly different between the two groups.

Intraoperative nitroglycerin administration was associated with a significantly lower rate of active segment uterine incision in patients undergoing CD and decreased maternal blood loss. Neonatal outcomes were similar between groups.