449. Management of microangiopathic haemolytic anaemia in pregnancy

Abstract

Microangiopathic haemolytic anaemia (MAHA) refers to haemolytic anaemia caused by small arteriole endothelial dysfunction. Pregnancy-induced changes to maternal vasculature, coagulation and immunity predispose women to MAHA. Materno-fetal disease follows platelet consumption within microthrombi of arterioles to end-organs and is often organ-specific. The key to successful management is accurate diagnosis. MAHA and microthrombi within the utero-placental circulation is associated with pre-eclampsia. Childbirth is the cure, but management is supportive until maternal or fetal condition deteriorate, or when fetal maturity is considered sufficient for ex-utero survival. HELLP syndrome describes the pathological components of MAHA affecting the liver. It presents suddenly with acute hepatic pain and an acute rise in liver transaminases with platelet consumption. HELLP is often associated with placental dysfunction, fetal growth restriction and hypertension. Management is similar to preeclampsia management. Steroids may improve the maternal platelet count and reduce the risk of peripartum bleeding. MAHA and microthrombi within the brain is suggestive of thrombotic thrombocytopaenic purpura (TTP). Women present with neurological symptoms, headache and seizures. TTP is secondary to low level of metalloproteinase ADAMTS13, which cleaves the endothelial von Willebrand factor and prevents platelet microthrombi. Levels of ADAMTS13 fall during pregnancy such that women with a congenital deficiency, or with autoantibodies against ADAMTS13, are predisposed to peripartum TTP. Treatment is plasma exchange. MAHA and microthrombi within the kidneys is suggestive of haemolytic uraemic syndrome (HUS). Pregnant women present with hypertension and acute kidney injury. Treatment of atypical HUS has been transformed by the introduction of Eculizimab that targets a component of the complement system. Acute fatty liver of pregnancy (AFLP) is a metabolic disorder characterised by a defect in fat metabolism. AFLP presents with multi-organ failure. This lecture will use a case-based approach to highlight features that discriminate between MAHA and allow implementation of targeted therapies to improve pregnancy outcome.