Thrombocytopenia in pregnancy

Abstract

Hematologists are often consulted for thrombocytopenia in pregnancy, especially when there is a concern for a non-pregnancy-specific etiology or an insufficient platelet count for the hemostatic challenges of delivery. The severity of thrombocytopenia and trimester of onset can help guide the differential diagnosis. Hematologists need to be aware of the typical signs of preeclampsia with severe features and other hypertensive disorders of pregnancy to help distinguish these conditions, which typically resolve with delivery, from other thrombotic microangiopathies (TMAs) (eg, thrombotic thrombocytopenic purpura or complement-mediated TMA). Patients with chronic thrombocytopenic conditions, such as immune thrombocytopenia, should receive counseling on the safety and efficacy of various medications during pregnancy. The management of pregnant patients with chronic immune thrombocytopenia who are refractory to first-line treatments is an area that warrants further research. This review uses a case-based approach to discuss recent updates in diagnosing and managing thrombocytopenia in pregnancy.

Graphical abstract

Figure 1.

Platelet count distribution. Shown are mean platelet counts of the non-pregnant women and the distribution of the mean platelet counts during first trimester and at time of delivery in women who had uncomplicated pregnancies. From N Engl J Med, Reese et al, Platelet Counts During Pregnancy, 379, 32-43. Copyright © 2018 Massachusetts Medical Society. Reprinted with permission from Massachusetts Medical Society.

Figure 2.

Relative frequency of etiology of thrombocytopenia during pregnancy by trimester. Relative frequency estimated based on review of literature and experience as described in Cines and Levine includes infection, disseminated intravascular coagulation, drug-induced thrombocytopenia, and bone marrow failure. *In a study by Reese et al, 1.8% of women with uncomplicated pregnancies had platelets <150 × 10⁹/L. Gestational thrombocytopenia was far more common in the second or third trimesters.

Figure 3.

Evaluation of thrombotic microangiopathies presenting in the second and third trimesters. This schema highlights recommended testing to distinguish preeclampsia with severe features/HELLP from cm-TMA or TTP. Not all possible etiologies to consider are listed in this brief schema. *ADAMTS13 testing may also be appropriate in patients with clinical picture consistent with HELLP syndrome to rule out TTP as an alternate etiology. ^†Other etiologies to consider with severe renal injury are severe hypertension or catastrophic antiphospholipid syndrome. PT/PTT, prothrombin/partial thrombplastin time.