Thrombocytopenia in Pregnancy: TTP or HELLP?
Ms. K, 38, at 30 weeks' gestation, presents with 3 days of bruising, confusion, and dark urine. Platelets 14 × 10^9/L, Hb 7.8 g/dL, MCV 92 fL, reticulocytes 8%, LDH 1,450 U/L, haptoglobin <10 mg/dL, creatinine 1.6 mg/dL, total bilirubin 3.2 mg/dL, AST 68 U/L, ALT 52 U/L. PT/INR 1.0, aPTT 28 s, fibrinogen 320 mg/dL, D-dimer 1.2 µg/mL. Peripheral smear shows 4–6 schistocytes per high-power field and no platelet clumps. Blood pressure 152/94 mmHg; urine dipstick protein 2+, blood 3+. The obstetric team asks whether to transfuse platelets before a planned cesarean delivery because the platelet count is 14 × 10^9/L. The patient is alert but has new confusion and a headache.
1. What is the most likely diagnosis, and how do the coagulation studies help distinguish it from DIC and HELLP?
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The picture is most consistent with immune-mediated thrombotic thrombocytopenic purpura (TTP). The key features are severe thrombocytopenia (14 × 10^9/L), microangiopathic hemolytic anemia (Hb 7.8, LDH 1,450, haptoglobin <10, schistocytes 4–6/HPF), neurologic symptoms, renal injury (creatinine 1.6, proteinuria, hematuria), and normal coagulation studies (INR 1.0, aPTT 28 s, fibrinogen 320, only mildly elevated D-dimer). DIC would typically prolong PT/aPTT, lower fibrinogen, and raise D-dimer more. HELLP can occur at 30 weeks and cause hemolysis, elevated liver enzymes, and low platelets, but the AST/ALT are only mildly elevated, the coagulation profile is normal, and the neurologic findings and schistocyte burden favor TTP. Confirm with ADAMTS13 activity; a level <10% establishes TTP.
2. Should platelets be transfused before cesarean delivery? Explain the reasoning.
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Do not give prophylactic platelets. In TTP, platelet transfusion can fuel microvascular thrombosis and has been associated with worsening. The platelet count of 14 × 10^9/L is dangerously low, but the immediate priority is plasma exchange, which removes autoantibodies and replenishes ADAMTS13. If cesarean delivery is truly urgent, coordinate with apheresis and obstetric anesthesia; platelets should be given only for active bleeding or a planned invasive procedure after weighing the thrombotic risk, and preferably after plasma exchange has begun. Neuraxial anesthesia usually requires a higher platelet count, so the decision should be made jointly. If the patient is bleeding or surgery cannot be delayed, transfuse platelets in small aliquots and document the indication.
3. What is the immediate management, and which test must be sent before therapy is started?
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Start urgent plasma exchange (1–1.5 plasma volumes daily) plus corticosteroids (e.g., prednisone 1 mg/kg/day or methylprednisolone). Send ADAMTS13 activity and inhibitor before the first exchange if possible, but do not delay treatment while waiting. If plasma exchange is unavailable, give fresh frozen plasma. Avoid platelet transfusion unless life-threatening bleeding. Monitor for cardiac and neurologic complications, and involve high-risk obstetrics, hematology, and apheresis. Delivery may be required for obstetric indications, but TTP itself is not an indication for immediate delivery; treat the mother and monitor the fetus. Rituximab can be added for refractory or relapsing disease, but the first-line decision is plasma exchange.