Immune Thrombocytopenia and Pregnancy Workup

Updated: Sep 21, 2020
  • Author: Shamudheen Rafiyath, MD; Chief Editor: Srikanth Nagalla, MD, MS, FACP  more...
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Workup

Approach Considerations

 

 

 

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Laboratory Studies

A baseline investigation of thrombocytopenia in pregnancy include the following:

  • Complete blood cell count (CBC)
  • Reticulocyte count
  • Peripheral smear examination
  • Coagulation screen
  • Liver function tests
  • Autoimmune disease screening
  • Virology screen
  • Vitamin B12, zinc, and folate levels

Spurious thrombocytopenia or pseudo-thrombocytopenia need to be ruled out by testing the platelet count in a citrate sample.

There is no diagnostic test to differentiate gestational thrombocytopenia and immune-mediated thrombocytopenia. Therefore, the diagnosis of immune thrombocytopenia (ITP) is based on a personal history of bleeding, a low platelet count prior to pregnancy, and/or a family history that excludes hereditary thrombocytopenia (HT). [6]  Platelet counts of less than 70,000/µL are suspicious for the disorder if no other etiology for thrombocytopenia is identified. [24]  Other testing, based on patient history and clinical findings, helps to rule out other possible etiologies for thrombocytopenia in pregnancy

The variation in the platelet count may be due to peripheral destruction of platelets or congenital platelet disorders. The appearance of schistocytes in the peripheral smear along with an increase in the lactate dehydrogenase l, elevated renal function, and anemia are evidence of thrombotic microangiopathy. The presence of abnormal white cell morphology, immature cells, and teardrop erythrocytes is suggestive of concomitant bone marrow pathology.

Bone marrow biopsy is needed in selected patients with signs and symptoms pointing to a lymphoproliferative disorder (fever, night sweats, weight loss, splenomegaly, and lymphadenopathy).

Antiplatelet antibodies can be detected in the serum of women with ITP. The direct assay for the measurement of platelet-bound autoantibodies has an estimated sensitivity of 49-66% and an estimated specificity of 78-92%. A negative test does not exclude the diagnosis. [25] Additionally, many women with gestational thrombocytopenia have high levels of circulating platelet-associated immunoglobulin. Therefore, current antiplatelet antibody assays cannot be used to differentiate between ITP and gestational thrombocytopenia.

In newborns, a platelet count less than 150,000/µL is consistent with thrombocytopenia. Consider neonatal alloimmune thrombocytopenia (NAIT) in the differential diagnosis of any significantly thrombocytopenic newborn (platelet count > 50,000/µL) or in newborns with intracranial hemorrhages (platelet count < 100,000/µL) in whom other illnesses commonly associated with thrombocytopenia have been excluded, as follows [21] :

  • Platelet antigen typing can determine the genotype of the mother and father of the baby to determine if they are discordant.

  • Test the maternal sera for the presence of a platelet antibody that binds paternal, but not maternal, platelets.

  • A lack of antiplatelet antibody does not exclude the diagnosis of NAIT because, in a number of cases, no antiplatelet antibody could be detected when fetuses were profoundly thrombocytopenic due to NAIT. [11]

 

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