Pregnancy-associated Thrombotic Thrombocytopenic Purpura: A Single Institution's Experience

Abstract 4675

Thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening form of microangiopathic hemolysis that can be associated with pregnancy. Although the association between TTP and pregnancy is well recognized, the presentation, natural history, and ideal treatment of TTP in this population remain poorly understood. St. Michael's Hospital is a regional referral centre for TTP in Ontario, Canada. We conducted a retrospective review of all cases of TTP referred to our pheresis unit between July 1993 and May 2010. Ninety-four cases were identified, of these, ten patients were pregnant or up to one week post-partum at the time of TTP diagnosis. Median age at presentation was 34 (29-36). Only one patient had been previously diagnosed with TTP and then developed a TTP relapse while pregnant. At presentation, all patients had thrombocytopenia (platelets: < 3 to 124 × 10⁶/ml), anemia (hemoglobin: 60 to 99 mg/L), elevated LDH (1.3 to 12.5 × ULN), and fragmentation on blood film. ADAMTS13 was assessed in six of ten patients. It was normal in four patients, and deficient in two patients. Seven patients had neurological symptoms at presentation, one of whom suffered permanent right sided paralysis. Six patients had depressed glomerular filtration ratio (GFR) at presentation, four of these six recovered normal GFR. Hypertension was present in only one patient, and no patients had abnormal coagulation parameters at presentation. ALT was normal in six patients, mildly elevated in two patients, and unavailable in two patients. There were no patient deaths in this series. Patients were treated with a median of 17 plasma exchanges (range: 9 to 55) using either fresh frozen plasma or cryosupernatant. Eight patients achieved complete remission with plasma exchange. Two patients had refractory disease which ultimately responded to splenectomy and rituximab respectively. There were two fetal deaths, one a first trimester miscarriage, and the second an intrauterine death in the second trimester. In conclusion, in our series of pregnancy associated-TTP, there were no maternal deaths and most women responded to a short course of plasma exchange. ADAMTS13 deficiency was uncommon in our series. Nonetheless, in our series, TTP was not difficult to distinguish from preeclampsia and/or disseminated intravascular coagulation using routine laboratory parameters.