Acquired thrombophilia in pregnancy: essential thrombocythemia.

The management of pregnant patients with essential thrombocythemia (ET) is a difficult problem. The clinical course of ET is mainly determined by thromboembolic complications. Pregnancy itself is a physiological hypercoagulable state. When ET affects women during pregnancy, an adverse outcome caused by thrombotic complications is a matter of concern. We reviewed 155 pregnancies in 86 women with ET. The success rate (baby alive) was 59%. First-trimester abortion was the most frequent complication and occurred in 31% of pregnancies. Placental infarction caused by thrombosis seemed to be the most consistent pathologic event. Maternal thrombotic or hemorrhagic complications were rare but were more common than those seen in normal pregnancy. Pregnancy itself does not appear to affect adversely the natural course and prognosis of ET. A meta-analysis revealed a significant benefit for aspirin in comparison to no treatment. If cytoreductive therapy becomes necessary, interferon alpha appears to be the drug of choice. The value of heparin prophylaxis has not been established but may have a role in selected cases.