Fibrin monomer complex as a potential thrombosis marker related to venous thromboembolism risk in pregnant women

Background Pregnancy is a risk factor for venous thromboembolism (VTE) due to increased coagulation factor activity and decreased protein S activity. However, thrombosis markers for predicting VTE in pregnancy remain controversial. This study aimed to investigate the relationship between VTE risk and thrombosis markers in pregnant women and to identify markers related to VTE risk. Methods Archived plasma samples from 107 pregnant women were used in this study, and the concentrations of D-dimer, fibrin monomer complex (FMC), plasmin-plasmin inhibitor complex, prothrombin time, activated partial thromboplastin time, and fibrinogen were measured. VTE risk was scored according to the Royal College of Obstetricians and Gynaecologists green-top guidelines and the patients were divided into low- or high-risk groups. Results The median (range) of risk score for deep vein thrombosis was 2 (0-8), and we defined the high-risk group included those with a score of >= 3. D-dimer and FMC concentrations were significantly higher in the high-risk group than in the low-risk group (D-dimer 4.5 vs 2.6 mu g/mL, p = 0.008; FMC 14.6 vs 3.4 mu g/mL, p < 0.001). Although D-dimer concentration significantly increased with gestational age (Spearman's correlation coefficient [r(s)] = 0.317, p < 0.001), FMC concentration did not (r(s) = -0.081, p = 0.409). The area under the receiver operating characteristic curve values of D-dimer, FMC, and both D-dimer and FMC for the high-risk group were 0.656, 0.713, and 0.738, respectively. Conclusions FMC may be a thrombosis marker related to VTE risk in pregnancy and is potentially preferable over D-dimer concentrations.