Comparative analysis of antidiuretic effects of oxytocin and carbetocin in postpartum hemorrhage prophylaxis: a retrospective cohort study

Objectives: To compare the antidiuretic effects of oxytocin and carbetocin in patients undergoing elective caesarean section. Methods: This retrospective cohort study included 276 participants who underwent elective singleton caesarean sections, with 184 receiving oxytocin and 92 receiving carbetocin. Exclusion criteria comprised patients with additional medical conditions or drug use affecting urine output, those diagnosed with postpartum hemorrhage, and those requiring non-standard intravenous fluid administration or additional uterotonics. Data on demographic characteristics, urinary output, time to reach specific urine output thresholds (500 mL, 1,000 mL, and 1,500 mL), vital signs, and hemoglobin levels were collected and compared between the oxytocin and carbetocin groups. Results: There were no significant differences in demographic characteristics between the groups. There were no significant differences in preoperative and postoperative hemoglobin levels, vital signs or duration of hospitalization between the two groups. The carbetocin group exhibited significantly higher total urine output in the first 6 h compared to the oxytocin group (p=0.037). The time required to achieve urine output volumes of 500, 1,000, and 1,500 mL did not differ significantly between groups. Conclusions: Carbetocin may exert a less pronounced antidiuretic effect than oxytocin following elective caesarean section in a cohort with as few confounding factors as possible. Further prospective studies are warranted to validate these findings and assess their clinical implications in postpartum hemorrhage prophylaxis.