Accuracy of Blood Loss Estimation and Identification of Factors Contributing to Early Postpartum Hemorrhage Following Vaginal Delivery

Objective: The study aimed to assess the accuracy of two distinct methods for estimating blood loss (EBL) and to identify potential factors contributing to early-onset postpartum hemorrhage (PPH) following a vaginal delivery (VD). Methods: Women in singleton pregnancies undergoing spontaneous/induced VD were recruited for this prospective observational cohort study. Methods of EBL included: (1) visual assessment by an attending obstetrician (sEBL) and (2) implementation of a mathematical formula (fEBL). Early PPH was defined as a cumulative blood loss exceeding 500 mL within the first 24 h after delivery as reflected by clinical assessment. Results: During the study period, 485 women delivered vaginally, and early PPH was diagnosed in 29 cases (5.97%). Among patients with PPH, a significant increase in the duration of the 2nd (61 min. vs. 33.5 min., p < 0.05) and 3rd (13 min. vs. 7 min., p < 0.001) stages of labor, as well as in the application of a dinoprostone insert (31% vs. 10.5%, p < 0.01) was noted. Additionally, in the same cohort, uterine atony (41.4% vs. 1.5%, p < 0.001), 3rd/4th degree perineal rupture (6.9% vs. 0%, p < 0.01), fetal macrosomia (17.2% vs. 4.8%, p < 0.05) and stillbirth (6.9% vs. 0.2%, p < 0.05) occurred significantly more frequently. In both groups visual estimation of blood loss was significantly lower compared to fEBL: (PPH sEBL: 800 mL vs. fEBL 1439.6 mL, p < 0.001; control sEBL: 250 mL vs. fEBL 621.8 mL, p < 0.001). In the multivariate analysis, factors such as third stage of delivery time ≥ 30 min. (OR 11.6; 95% CI: 4.18-32.33), FBW ≥ 4000 g (OR 6.37; 95% CI: 1.54-26.3), and dinoprostone insert application (OR 4.33; 95%CI: 1.63-11.48) were selected as independent predictors of the PPH. Conclusions: Compared to mathematical formula, visual estimation of blood loss by an attending obstetrician is significantly decreased. Prolonged third stage of delivery, fetal macrosomia, and application of a dinoprostone insert are the strongest contributors to early PPH following a VD.