Efficacy of Carbetocin and Oxytocin in Reducing Blood Loss during the Third Stage of Labour: A Prospective Observational Study

Introduction: Postpartum Haemorrhage (PPH) remains a leading cause of maternal morbidity and mortality. Prophylactic uterotonics like oxytocin are widely used; however, newer agents such as carbetocin have emerged as potential alternatives with longer half-lives and reduced need for repeated administration. Aim: To compare the efficacy and safety of carbetocin versus oxytocin in preventing PPH during vaginal delivery. Materials and Methods: The present prospective observational study was conducted in the Department of Obstetrics and Gynaecology of Amala Institute of Medical Sciences in Kerala, India from December 2022 to December 2023, including 260 women undergoing vaginal delivery. A total of 130 women were administered carbetocin (100 µg) as a single intravenous dose and 130 women were given oxytocin according to Kerala Federation of Obstetrics and Gynaecology (KFOG) guidelines i.e., five units oxytocin diluted in 5 mL Normal Saline (NS) slow Intravenous (i.v.) over five seconds+10 units Intramuscular (IM)+20 units infusion in 500 mL NS at one drop/sec. Primary outcomes included incidence of PPH, estimated blood loss, and the need for additional uterotonics. The Estimated Blood Loss (EBL) was assessed using gravimetric analysis. Haemodynamic parameters were also recorded at five minutes and 30 minutes. Any adverse events and requirement of blood transfusion were also noted. Associations between categorical variables were tested using Chi-square or Fisher’s exact test, while associations between continuous variables were evaluated using the independent t-test, with statistical significance set at the 5% level. Results: In the present study, mean age was 26.08±3.32 years in the oxytocin group and 27.07±3.85 years in the carbetocin group, with predominantly primigravida women (69, 53.1% vs 73, 56.2%) Also, 13 (10%) of the carbetocin patients experienced >500mL blood loss versus 9 (6.9%) in the oxytocin group. Mean estimated blood loss was similar (carbetocin: 316.28 mL; oxytocin: 311.77 mL, p=0.871), as was the need for additional oxytocics (carbetocin: 16 (12.3%); oxytocin: 15 (11.5%), p=0.848). Only one oxytocin patient (0.8%) required transfusion. Vomiting occurred in 2.3% of carbetocin patients, with none in oxytocin. Carbetocin showed a statistically significant slight increase in Systolic Blood Pressure (SBP) at five minutes was +0.892±10.23 mmHg (oxytocin) versus +1.354±6.32 mmHg (carbetocin), p=0.034. Conclusion: Carbetocin demonstrates comparable efficacy to oxytocin in reducing blood loss and preventing PPH during vaginal delivery.