Platelets have been implicated in the development of preeclampsia and may be activated weeks before clinical symptoms appear. Even in normal pregnancy a hypercoagulable state exists, and the risk of thrombosis is even higher in the puerperal period. Because of past difficulty in obtaining blood samples from discharged patients, researchers collected blood samples at home from 11 preeclamptic women whose blood pressures averaged 170/108 mm Hg. Seven were nulliparas, and gestational age at delivery averaged about 36 weeks. Eleven normotensive parturients formed a control group. Seven women in each group had cesarean delivery.
Preeclamptic women had a significant rise in the number of platelet from 6 to 14 days postpartum, with an average increase from 240 to 621 × 109/liter. Earlier postpartum counts did not differ significantly from antepartum counts. Control women also had a significant increase in platelet counts, reaching a mean peak of 351 × 109/liter, 6 to 14 days after delivery. Peak counts were significantly higher in the preeclamptic group at this stage, as was the increase from antepartum to postpartum values. Platelet volumes were significantly higher in preeclamptic than in control women before delivery. A postpartum decline in both groups eliminated any group difference. In neither group did estimated blood loss correlate with the postpartum platelet count, and women in the two groups lost comparable amounts of blood.
Platelet counts increased 2- to 3-fold in preeclamptic women in the second postpartum week compared with women who remained normotensive during pregnancy. The authors suggest that it may be helpful to estimate platelet numbers in high-risk patients after they are discharged. High-risk patients include those with severe preeclampsia and the hemolysis, elevated liver enzymes, low platelets syndrome, especially those who had a cesarean delivery or have other risk factors, such as obesity, older age, or postpartum infection. Measures intended to prevent thrombosis should be considered when such patients exhibit delayed rebound thrombocytosis in the postpartum period.
Acta Obstet Gynecol Scand 1999;78:866–870