Coagulation index to distinguish severe preeclampsia from normal pregnancy.

The purpose of this study was to establish a new coagulation index to distinguish severe preeclampsia from normal pregnancy using optimal coagulation parameters. The difference between platelet counts in early gestation and before delivery (DeltaPlt = [platelet counts before delivery] - [platelet counts in early gestation]) was calculated as an index of changes in platelet counts. Antithrombin (AT) activity, thrombin-antithrombin (TAT) complex, fibrin degradation products (FDP) D-dimer, and DeltaPlt were investigated in 72 cases of normal pregnant women in the third trimester of pregnancy and 56 cases of severe preeclampsia. The new coagulation index was calculated using multivariate logistic regression analysis. As a result, in a case using four parameters, the following formula was obtained: Y = (-0.019 x AT activity) + (0.067 x TAT) + (0.067 x D-dimer) + (-0.064 x DeltaPlt) + 0.706. According to this formula, coagulation indices in normal pregnant women and in patients with severe preeclampsia were -0.77 +/- 0.51 and 1.41 +/- 1.56, respectively (p < 0.0001). Among patients with severe preeclampsia, coagulation and fibrinolysis disorders before delivery were typical in patients terminated by cesarean section (coagulation index = 1.62 +/- 1.66) compared with those with successful vaginal delivery (coagulation index = 0.52 +/- 0.34) (p < 0.05). These facts suggest that an excessive hypercoagulable state is associated with the termination of pregnancy resulting from the aggravation of preeclampsia. From the viewpoint of coagulation and fibrinolysis disorders, the predictive value in order to decide the optimal time for the termination of pregnancy could be recommended when the coagulation index exceeded 1.20.