Abstract

Pregnancy is an initiating event for acute thrombotic thrombocytopenic purpura (TTP). Patients with a history of TTP have a high risk of relapse during pregnancy with associated maternal and fetal morbidity/mortality. We report 5 TTP patients who underwent serial clinical and laboratory monitoring (haemoglobin, platelets, blood film, reticulocytes, lactate dehydrogenase (LDH), ADAMTS-13 activity and IgG antibodies) and treatment within a specialist obstetric/haematology clinic, resulting in successful pregnancy outcomes. Patients: Cases 1 and 2 presented with TTP in their first pregnancy and had second trimester fetal losses. Case 3 had four TTP relapses and soon after achievement of clinical remission became pregnant. Case 4 had a single acute episode of TTP 6 years prior to pregnancy and normal ADAMTS 13 activity at the onset of pregnancy. Case 5 presented with acute TTP and a left sided stroke at 16 weeks gestation. ADAMTS-13 activity was <5% at onset of pregnancy in cases 1–3 and at presentation of TTP during pregnancy in case 5. Only case 3 had IgG antibodies to ADAMTS13. Cases 1–3 received regular plasma exchange (PEX) every 2 weeks initially, starting during the first trimester, with ADAMTS 13 activity levels maintained >15% during pregnancy (range 15–78%, normal range 66–126%) by collagen binding assay. Case 4 had normal laboratory parameters, including serial ADAMTS 13 activity levels, throughout pregnancy, requiring no specific therapy for TTP. Case 5 received intensive PEX (84 procedures) and pulsed methylprednisolone during pregnancy. Rituximab (375mg/m2, weekly for 4 weeks) was given at 28 weeks gestation with no observed toxicity except asymptomatic transient neonatal neutropenia. All 5 cases continued low dose aspirin (75 mg daily) throughout pregnancy. Case 1 and 2 received prophylactic low molecular weight heparin (LMWH) and cases 3 and 5 received treatment doses of LMWH for pulmunory emboli and TTP associated stroke at presentation. Live healthy infants were delivered in all 5 cases in the third trimester (31–41 weeks). These data suggest successful pregnancy outcome is achievable in patients with a history of TTP/acute TTP with therapy based on close clinical and laboratory monitoring. Regular PEX in patients with a history of TTP and severely reduced ADAMTS 13 activity/IgG antibodies to ADAMTS 13 at the onset of pregnancy was associated with successful pregnancy outcome. Serial ADAMTS 13 activity and antibody levels during pregnancy and post-partum provided a useful adjunct to decision making on intensity of treatment.

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