The impact of indication for cesarean on blood loss.

Background: Postpartum hemorrhage is the leading cause of maternal mortality worldwide. Quantitative blood loss assessment during cesarean delivery is a more accurate measure of blood loss than simple estimation. Risk factors for postpartum hemorrhage are well described. However, contemporary systematic investigations on the effect of indications for cesarean delivery on quantitative blood loss are lacking.

Objective: This study aimed to investigate whether there are clinically significant differences in quantitative blood loss and postpartum hemorrhage risk based on the indication for cesarean delivery.

Study Design: A total of 4881 cesarean deliveries performed at a large academic hospital between 2020 and 2022 were identified. Primary and repeat cesarean deliveries were analyzed separately and further subdivided into 7 indications: elective, labor arrest, fetal heart rate abnormalities, placenta previa, placenta accreta, malpresentation, and other. Quantitative blood loss and rates of postpartum hemorrhage (>1000 and >1500 mL) were compared among the different indications.

Results: The mean quantitative blood loss estimates for primary, repeat, and total cesarean deliveries were 886, 697, and 792 mL, respectively. Excluding cases of placenta accreta, the greatest blood loss in both primary and repeat groups was observed in cesarean deliveries performed for labor arrest, with blood loss exceeding 1500 mL in 18% and 13% of all cases. Blood loss exceeding 1500 mL was noted in 1% and 2% of elective cesarean deliveries. The mean blood loss for planned repeat cesarean deliveries/hysterectomies for placenta accreta was <400 mL greater than that for primary cesarean deliveries performed for labor arrest (1442 vs 1065 mL, respectively), despite the addition of an often-complex hysterectomy to the procedure.

Conclusion: Clinically and statistically significant differences in blood loss exist based on the indication for cesarean delivery. Large differences in the rates of serious postpartum hemorrhage (>1500 mL) with negligible differences in mean quantitative blood loss suggest the presence of frequent, large clinical outliers not reflected in a statistical mean. The indication for cesarean delivery and the possibility of such outliers rather than the predicted "average blood loss for cesarean delivery" should be considered when determining risk and the degree of necessary preoperative blood preparation. These data raise questions about whether current traditional techniques of cesarean delivery not associated with placenta accreta can be justified in nonemergent cases when such procedures can be performed with significantly less blood loss using techniques specific for placenta accreta.