Algorithm for classifying the underlying pathologies in postpartum hemorrhage using bleeding rate, fibrinogen, and fibrin/fibrinogen degradation products: a case series study

Abstract Background Understanding patients’ underlying pathologies is essential for appropriate treatment during postpartum hemorrhage (PPH) management. The objective of this study is to develop an algorithm that quantitatively classifies the underlying pathologies in PPH using clinical parameters. Methods A multicenter case series study involving nine perinatal centers in Japan was conducted on patients with severe PPH (blood loss > 2000 mL) excluding placental abruption, and placental abruption irrespective of blood loss spanning August 2020 to June 2024. The primary outcome was the development of an algorithm for classifying the underlying pathologies in PPH, based on bleeding rate, fibrinogen, and fibrin/fibrinogen degradation products (FDP). We used collected data to develop an algorithm by which cases with abnormally high bleeding rate (≥ 61 mL/min) were classified as whole blood loss with high bleeding rate (WBLH). Of cases with bleeding rate < 61 mL/min, those with fibrinogen ≥ 237 mg/dL were classified as non-coagulopathy (NCP). Of cases with fibrinogen < 237 mg/dL, those with FDP < 2 mg/dL and FDP ≥ 2 mg/dL were classified as whole blood loss with low bleeding rate (WBLL) and coagulation factor consumption (CFC), respectively. In CFC cases, a predictive formula distinguished between disseminated intravascular coagulation (DIC) from locally initiated and progressive consumptive coagulopathy for hemostasis (LIPC). We used the Mann–Whitney test and Fisher’s exact test for the statistical analysis. Results Among 171 participants, comprising 131 severe PPH cases and 40 placental abruption cases, the algorithm classified cases into WBLH ( n = 9), NCP ( n = 88), WBLL ( n = 12), and CFC ( n = 62). Of the CFC cases, 3 had DIC and 59 had LIPC. FDP levels did not differ between WBLH (median, 1.19 mg/dL) and WBLL (median, 0.91 mg/dL). Hemoglobin (median, 6.3 g/dL) in WBLL and fibrinogen (median, 168.5 mg/dL) in CFC were significantly lower than for the other three categories ( P < 0.05). Coagulation-fibrinolytic activation in DIC was significantly increased compared with LIPC cases. Conclusions Our algorithm, using bleeding rate, fibrinogen, and FDP as clinical parameters, classified PPH cases into four underlying pathologies. This pilot study provides a foundation for pathophysiology-based clinical management of PPH.