Late Onset Postpartum Thrombocytosis in Preeclampsia

Abstract

Background. During pregnancy, changes in blood coagulation and fibrinolysis create a hypercoagulable state. In the puerperium this thrombogenicity is even higher, and the chance of developing thromboembolism is 3-5 times higher in this period than during pregnancy. In preeclampsia, platelets are activated and play a substantial role in the pathogenesis of the disease. Systematic information on longitudinal changes in platelet number and size postpartum after normotensive and preeclamptic pregnancies is not available. Methods. We measured platelet number, mean platelet volume and the median volume of the 20% largest platelets in eleven preeclamptic and eleven normotensive pregnant women matched for mode of delivery. The blood samples were taken antepartum and every 2-3 days in the postpartum period until the platelet count decreased/normalized. Results. In the preeclamptic group, the platelet count increased significantly from 240×10 9 /l antepartum to 621×10 9 /l on day 6-14 postpartum (p<0.01). In the control group, the platelet count increased from 214×10 9 /l antepartum to 251×10 9 /l on day 2-5 (p<0.01) and 351×10 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 platelets were significantly higher in the preeclamptic than in the control group. Conclusion. The platelet count is significantly increased postpartum both after normotensive, and 2-3 fold more after preeclamptic pregnancies. The time to peak values is between 6-14 days, usually at a time when patients are discharged from hospital.