Validation of a quantitative system for real-time measurement of postpartum blood loss

Reliable real-time estimation of blood loss is crucial for the prompt management of postpartum hemorrhage (PPH), which is one of the major obstetric complications worldwide. Our study aims at the validation of feasibility and precision of measured blood loss (MBL) with a quantitative real-time measurement system during (1) vaginal delivery and (2) cesarean section by comparison with a hemoglobin-based formula for blood loss as an objective control. This is the first study to include a reasonable number of patients in an everyday clinical setting.

921 patients were prospectively enrolled into this study (vaginal delivery: n = 461, cesarean delivery: n = 460) at a tertiary care hospital in Switzerland. Blood loss was measured by quantitative fluid collection bags. "Calculated blood loss" (CBL) was determined by modified Brecher`s formula based on the drop of hemoglobin after delivery. MBL based on our measurement system was compared to CBL by correlation analysis and stratified by the mode of delivery.

During vaginal delivery, MBL as determined by our quantitative measurement system highly correlated with CBL (p < 0.001, r = 0.683). This was also true for patients with cesarean deliveries (p < 0.001, r = 0.402), however, in a less linear amount. In women with cesarean deliveries, objectively low blood loss tended to be rather overestimated, while objectively high blood loss was more likely underestimated.

The technique of real-time measurement of postpartum blood loss after vaginal delivery as presented in this study is practicable, reliable and strongly correlated with the actual blood loss and, therefore, poses an actual improvement in the management of PPH.