Late onset postpartum thrombocytosis in preeclampsia

Background During pregnancy, changes in blood coagulation and fibrinolysis create a hypercoagulable state. In the puerperium this thrombogenicity is e ven higher, and the chance of developing thromboembolism is 3-5 times highe r in this period than during pregnancy In preeclampsia, platelets are activ ated and play a substantial role in the pathogenesis of the disease. System atic information on longitudinal changes in platelet number and size postpa rtum after normotensive and preeclamptic pregnancies is not available. Methods. We measured platelet number, mean platelet volume and the median v olume of the 20% largest platelets in eleven preeclamptic and eleven normot ensive pregnant women matched for mode of delivery The blood samples were t aken antepartum and every 2-3 days in the postpartum period until the plate let count decreased/normalized. Results. In the preeclamptic group, the platelet count increased significan tly from 240 x 10(9)/l antepartum to 621 x 10(9)/l on day 6-14 postpartum ( p<0.01). In the control group, the platelet count increased from 214 x 10(9 )/l antepartum to 251 x 10(9)/l, on day 2-5 (p < 0.01) and 351 x 10(9)/l on day 6-14 postpartum (p<0.01). The platelet count was significantly higher in the preeclamptic than in the control group 6-14 days postpartum (p<0.01) . Antepartum, mean platelet volume and the median of the 20% largest platel ets were significantly higher in the preeclamptic than in the control group . Conclusion. The platelet count is significantly increased postpartum both a fter normotensive, and 2-3 fold more after preeclamptic pregnancies. The ti me to peak values is between 6-14 days, usually at a time when patients are discharged from hospital.