(1064) Effect of Intraoperative Sublingual Nitroglycerin on Active Segment Uterine Incision Rate in Preterm Cesarean Delivery

Objective: Active segment uterine incisions, including classical, T-shaped and high transverse incisions are often performed during preterm cesarean deliveries (CD). These uterine incisions increase the risk of maternal morbidity with longer operative time, increased blood loss, and 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 and Bandl’s rings. Our primary aim was to determine if intraoperative sublingual nitroglycerin is associated with decreased active segment uterine incision rate in patients undergoing CD prior to 30 weeks of gestation. Secondary outcomes included maternal blood loss, umbilical artery pH, and five minute APGAR scores.

Study Design: In this case control study, patients with singleton pregnancy between 22 weeks 0 days and 29 weeks 6 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, Mann-Whitney U tests as appropriate.

Results: 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 nitroglycerin intraoperatively (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 583mL compared to 794mL in patients who did not (p=0.002). Neonatal outcomes including umbilical artery pH and APGAR scores were not found to be significantly different between the two groups.

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