Laboratory testing is needed to identify low platelet levels but should also be evaluated carefully for abnormalities in the erythrocytes or immature, dysplastic, or monomorphic cells that could indicate the presence of a systemic hematologic disorder. Other patients may warrant more extensive testing depending on their medical or family history and initial examination; such testing may include evaluating markers of hemolysis (lactic acid dehydrogenase, haptoglobin, and reticulocyte counts), a basic metabolic panel, liver function tests, testing for infections (HIV, hepatitis B, and hepatitis C), thyroid function tests, and assessment for antiphospholipid antibodies.
The management of thrombocytopenia differs depending on the etiology of the disorder, explained Dr Pishko. “Etiologies such as gestational thrombocytopenia do not generally affect the mother or baby, and in gestational thrombocytopenia, the thrombocytopenia resolves after delivery.”
For other pregnancy-specific etiology (such as HELLP syndrome or severe preeclampsia), treatment involves urgent delivery of the baby, though this may lead to preterm deliveries. “In ITP, the mother may require therapy to increase the platelet count to allow for a safe delivery and epidural catheter placement,” Dr Pishko explained. “However, some mothers with ITP do not require any therapy if their platelet count is in a safe range.”
Although its underlying mechanisms are unclear, gestational thrombocytopenia is not associated with an increased risk of maternal bleeding. Special precautions are not required for delivery in these cases as no risk of clinically significant thrombocytopenia is conferred to newborns.
Thrombocytopenia associated with hypertensive disorders, including preeclampsia, eclampsia, HELLP syndrome (which may be a severe variant of preclampsia) and acute fatty liver of pregnancy, is the second leading cause of thrombocytopenia in pregnancy. Preeclampsia is diagnosed in 3.8% of pregnancies in the United States, and 1.4% of pregnancies involve severe symptoms or eclampsia. Thrombocytopenia can sometimes be the only initial sign of this condition, appearing before other laboratory changes. In these cases, treatment decisions are based on gestational age at diagnosis as well as symptom severity. For example, delivery is indicated for all women with severe preeclampsia who are at 34 weeks or greater. Other treatments for severe hypertension include intravenous labetalol, hydralazine, and oral short-acting nifedipine, and magnesium sulfate ought to be administered to patients with severe symptoms to prevent seizures.
ITP, which accounts for approximately 3% of all cases of thrombocytopenia in pregnancy, is caused by autoantibodies that accelerate platelet clearance and inhibit their production. A condition known as Evans syndrome can occur concurrently with ITP, causing autoimmune hemolytic anemia. Management depends on several factors, including platelet count and how close the patient is to delivery. In the absence of bleeding, for example, treatment is not needed for a platelet count of at least 30 × 109/L unless the patient is approaching delivery. Platelet counts should be monitored at least monthly and more frequently after 34 weeks of gestation, especially if the patient’s platelet count is below 80 × 109/L. The authors noted that this threshold is often used by anesthesiologists for neuraxial anesthesia and to avoid the need for platelet transfusions or other emergency measures during delivery. For patients with ITP who need treatment, corticosteroids or intravenous immunoglobulin are first-line therapies. Neonatal platelet levels should also be assessed at birth and monitored daily.
Overall, diagnosing and managing thrombocytopenia in pregnant patients requires paying close attention to both personal and family medical histories, pregestational platelet counts, symptoms’ time of onset and severity, and accompanying clinical and laboratory findings.
“Recognition of the etiology of thrombocytopenia and careful multidisciplinary management with obstetrics and hematology are needed,” noted Dr Pishko.
Disclosures: Some authors have declared affiliations with the pharmaceutical industry. Please refer to the original study for a full list of disclosures.
1. Pishko AM, Levine LD, Cines DB. Thrombocytopenia in pregnancy: diagnosis and approach to management [published online November 6, 2019]. Blood Rev. doi:10.1016/j.blre.2019.100638