Introduction:
Thrombotic thrombocytopenic purpura (TTP) is a rare but important cause of thrombocytopenia in pregnancy with an incidence of 1 in 200 000 pregnancies (1). We describe a case of acute onset TTP at 36 weeks gestation, successfully treated with plasma exchange (PEX) and delivered uneventfully by caesarean section under spinal anaesthesia.
Case report:
A 40 year old primigravida was transferred from a provincial hospital with severe thrombocytopenia and haemolysis. She was asymptomatic other than minor gum bleeding and intermittent epistaxis. Initial investigations revealed a platelet count of 12, haemoglobin of 112 and haptoglobins of <0.2. Severe pre-eclampsia, HELLP syndrome and acute fatty liver were excluded as likely differentials. She received 2 units of FFP and methylprednisone to cover for possible acquired TTP, before commencing PEX with a subsequent steady rise in platelet count to 163 over the following 3 days. Induction of labour was attempted but was unsuccessful, and she proceeded to an uncomplicated caesarean section under spinal anaesthesia. Her platelet count remained stable in the postnatal period and she was discharged home 4 days later. A low ADAMTS13 level (<1%) with no detectable autoantibody confirmed the diagnosis.
Discussion:
TTP is a rare, acute and potentially life-threatening disorder that typically affects women and can be precipitated by pregnancy. It comprises thrombocytopaenia, haemolytic anaemia and microvascular thrombosis, and has an untreated mortality of 90%. Women presenting with a new diagnosis of TTP in pregnancy typically do so in the third trimester or postpartum (2), and are more likely to have a congenital than acquired aetiology (2). TTP should be suspected in a case of severe thrombocytopaenia in pregnancy, however differentiating it from other causes such as severe pre-eclampsia, HELLP or acute fatty liver can be challenging. Specialist haematology advice should be sought as prompt treatment with plasma exchange is potentially life-saving. In the event of improvement in platelet count, delivery by caesarean section can be successfully performed under spinal anaesthetic.