Thrombotic microangiopathy (TMA) can be a key feature of several pregnancy related disorders such as thrombotic thrombocytopenic purpura (TTP ) / Haemolytic uremic syndrome (HUS), congenital TTP(CTTP), HELLP syndrome, or acute fatty liver (AFL). TMA is a life threatening condition in pregnancy. It encompasses a spectrum of different disorders with a similar pathogenesis, but in most of the cases completely different therapy. It can take several days to obtain the diagnosis, and in case of doubt therapeutic plasma exchange (TPE) (plasmapheresis with plasma substitution) should be started immediately to ensure better outcome. By measuring the activity of the von Willebrand-factor-cleaving protease (ADAMTS13), it may be possible to distinguish between the different causes of thrombotic microangiopathy. Pregnancy-related TMA can occur before or after birth. A Pregnancy-related TMA that develops during the puerperium, typically develops about the fourth day postpartum. No other significant differences are seen between antepartum and postpartum pregnancy related TMA. In critically ill patients it may be difficult to distinguish TMA from sepsis with disseminated intravascular coagulation (DIC). DIC is generally associated with prolongation of global clotting times, prothrombin time and activated partial thromboplastin time (PTT, aPTT) due to consumption of clotting factors. TMA occurs by primary activation of platelets (congenital or acquired abnormalities of ADAMTS13), and by primary endothelial injury (as with HELLP syndrome). Antepartum pregnancy-related TMA usually occurs at 28 ± 8 weeks of pregnancy.

(BELG J HEMATOL 2013;1:29–35)