[Thrombotic thrombocytopenic purpura--a rare and difficult differential diagnosis to HELLP syndrome in late pregnancy].

Thrombotic thrombocytopenic purpura (TTP) represents a rare complication mainly in the second trimester and can, in its early stage, mimic HELLP syndrome. At 38 weeks of gestation, a 40-year-old primigravida with elevated blood pressure, thrombocytopenia and elevated liver enzymes was diagnosed with HELLP syndrome. Despite a Ceasarean section her laboratory parameters remained pathological with severe thrombocytopenia and hemolysis. In addition, the patient developed neurological comatose-like symptoms. The diagnosis of TTP was made after further tests revealed fragmented red cells in the blood, autoantibodies against ADAMTS13 and a nearly total loss of ADAMST13 plasma activity. The patient fully recovered following repeated plasmapheresis and plasma substitution as well as systemic treatment with dexamethasone. If laboratory parameters do not normalise promptly in spite of the correct treatment for an assumed HELLP syndrome, TTP may be the underlying pathology. As rapid assays for antibodies against ADAMTS13 are not available yet, special consideration must be given to the clinical details in order to make a correct diagnosis.