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 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 240x10(9)/l antepartum to 621x10(9)/l on day 6-14 postpartum (p<0.01). In the control group, the platelet count increased from 214x10(9)/l antepartum to 251x10(9)/l on day 2-5 (p<0.01) and 351x10(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.