https://www.ajog.org/article/S0002-9378(24)01047-0/abstract

Background

Postpartum hemorrhage is the leading cause of maternal mortality worldwide. Quantitative blood loss assessment at the time of cesarean delivery is a more accurate measure of blood loss than is simple estimation. Risk factors for postpartum hemorrhage are well described; however, contemporary, systematic investigations into the impact of the indication for cesarean delivery on quantitative blood loss are lacking.

Objective

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 cohort of 4,881 cesarean deliveries performed at a large academic hospital between 2020 and 2022 was identified. Primary and repeat cesarean deliveries were analyzed separately and further subdivided into seven indications: elective, labor arrest, fetal heart rate abnormalities, placenta previa, placenta accreta, malpresentation, and other. Quantitative blood loss and rates of postpartum hemorrhage ( > 1000 cc and >1500cc) were compared among the different indications.

Results

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

Conclusions

Clinically and statistically significant differences in blood loss exist based on the indication for cesarean delivery. Large differences in rates of serious postpartum hemorrhage (>1500cc) with negligible differences in mean quantitative blood loss suggests the presence of frequent, large clinical outliers not reflected in a statistical mean. The indication for cesarean and the possibility of such outliers, rather than the predicted “average blood loss for cesarean delivery” should be considered in determining risk and the degree of necessary pre-operative blood preparation. These data raise questions about whether current, traditional techniques of non-accreta related cesarean delivery can be justified in non-emergent cases when such procedures could be performed with significantly less blood loss using accreta-specific techniques.