Fibrin monomer complex in normal pregnant women: a potential thrombotic marker in pregnancy

Background Pregnancy represents a major risk factor for deep vein thrombosis (DVT). Most coagulation/fibrinolysis markers currently utilized change during pregnancy, and therefore they cannot accurately evaluate thrombotic events in pregnancy because the rate of false positive results is high. Fibrin monomer complex (FMC) has recently become widely available for diagnosing DVT. The present study examined whether FMC is suitable for evaluating thrombotic status in pregnancy. Methods Concentrations of FMC and other haemostatic markers were investigated in 87 pregnant women without major complications at early, mid- or late pregnancy. FMC concentrations were also measured in 127 normal nonpregnant women, and in one woman who developed DVT after delivery. Results In normal pregnant women, FMC concentrations were unchanged during early or mid-pregnancy and slightly elevated during late pregnancy. Concentrations were within reference range in most cases, and none exceeded the cut-off value for DVT. In contrast, thrombin-antithrombin complex (TAT) and D-dimer (DID) concentrations were significantly elevated in late pregnancy, and median values exceeded reference ranges. The DVT case displayed significantly elevated FMC concentrations. Conclusions Changes in FMC concentrations during normal pregnancy are minimal compared with other haemostatic markers. Because the rate of false positivity is lower, FMC could be a potential marker of thrombotic status in pregnancy rather than TAT and DID.