Essential thrombocythemia (ET) is one of the myeloproliferative disorders characterized by an elevated platelet count, usually greater than 1,000 X 10(9)/L. It may be associated with either hemorrhagic or thrombotic tendencies. Although it usually affects older people, we have recently encountered two young women with ET who had a total of six spontaneous abortions before the end of the first trimester. During her most recent pregnancy, one of the patients underwent plateletpheresis on four separate occasions before the 12th week. She reached 34 weeks but demonstrated evidence of fetal growth retardation and pre-eclampsia. At delivery there were scattered villus infarcts in the placenta. Based on this patient and previous reports in the literature, we postulate that the spontaneous abortions, fetal growth retardation, and pre-eclampsia may be related to the thrombocytosis and suggest that the use of antiplatelet agents throughout pregnancy should be seriously considered in such cases.
Recent reviews support the observation that essential thrombocytosis in young patients is not always without risk. Thrombotic complications include acute myocardial infarction and stroke [l, 21 in addition to recurrent abortions and stillbirths presumably related to placental infarction [3-51. At the time of our previous report, our second patient had been lost to follow-up. She recently was seen in another centre at which time she was pregnant for the eighth time. She reported a total of seven spontaneous abortions occurring around the end of the first trimester. The platelet count was 669-714 X 109/L. She was placed on aspirin 325 mg daily and continued on this through pregnancy. She presented to the hospital at 38 weeks with mild pregnancy-induced hypertension and evidence of intrauterine growth retardation. A female infant weighing 2.325 kg was delivered by cesarean section (Apgar at 1 and 5 min, 8 and 9). Examination of the placenta revealed a large, old subchorionic infarction. After a short stay in the neonatal intensive care unit, the infant was discharged with the mother. Postpartum, the platelet count remained elevated at 942 X 109/L. These observations further support the hypothesis that essential thrombocythemia predisposes to spontaneous abortions and stillbirths, presumably by causing placental infarctions, and that aspirin given throughout the pregnancy can lead to a favorable outcome.of Pregnancy
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