Estimation of postpartum blood loss: Validation of a quantitative measurement system in the daily obstetric setting

Background:

Postpartum hemorrhage is one of the major complications for women during labor. Still there is uncertainty how to measure postpartum blood loss most accurately in the daily obstetric setting, despite its importance for direct treatment measures.

Our study aims at validation of estimation of postpartum blood loss by the application of a hemoglobin based formula (Brecher's formula) for blood loss as an objective control. The patients were stratified for mode of delivery with a separate analysis for vaginal deliveries and cesarean deliveries.

Methods:

921 patients were prospectively enrolled into this study. Blood loss during vaginal delivery was visually estimated by midwives and obstetricians and the bloody drapes were regularly weighed. In case of a weighed bleeding amount of more than 300 ml, a fluid collection bag with a quantitative scale was installed for the most accurate measurement of postpartum blood loss. During cesarean deliveries, blood loss was estimated with the help of fluid collection bags. Additionally, “calculated blood loss” was determined by Brecher's formula based on the drop of hemoglobin postpartum (Volume of Blood Loss = Estimated Blood Volume x ln (hemoglobin level before delivery/postpartum hemoglobin level)). Estimated blood loss based on our measurement system was compared to calculated blood loss separately for vaginal and cesarean delivery by Pearson's correlation analysis.

Results:

After vaginal deliveries, estimation of postpartum blood loss with our quantitative measurement system highly correlated with calculated blood loss (p< 0.001, r = 0.683). In patients with cesarean deliveries, estimation of blood loss also correlated with calculated blood loss (p< 0.001, r = 0.402), however correlation was not as strong. Our data analysis revealed that in women with cesarean deliveries, objectively low blood loss tended to be overestimated while in patients with high blood loss, this condition was rather underestimated.

Conclusions:

Our study reveals two main findings with direct impact on the management of postpartum hemorrhage. First, the technique of postpartum blood loss estimation after vaginal delivery at our institution is practicable, reliable and strongly correlating with calculated blood loss. Second, blood loss during cesarean deliveries tends to be overrated in patients with low blood loss and, more importantly, underestimated in patients with increased blood loss.