New in the differential diagnosis of different variants of thrombotic microangiopathies in obstetrics

Abstract

All variants of thrombotic microangiopathy (TMA) in obstetric practice develop in an avalanche-like manner and require a rapid decision on the choice of treatment tactics. Although all these diseases have similar features, typical of the TMA syndrome as a whole, they are separate diseases with differing etiology and pathogenesis. Because the manifestations of TMA are almost identical in the different diseases, they may all imitate pre-eclampsia and the therapeutic approaches differ, a differential diagnosis is essential and often determines the prognosis.The differential diagnostic search between the different TMA variants that can develop in pregnancy is described, as the prognosis of life often depends on the correct diagnosis. The main differences between pre-eclampsia/HELLP syndrome and life-threatening conditions such as atypical hemolytic-uremic syndrome, thrombotic thrombocytopenic purpura and catastrophic antiphospholipid syndrome are considered. Algorithms of diagnostic search are proposed. Attention is drawn to the fact that existing algorithms for the diagnosis of severe TMA prior to ADAMTS 13 results, based on the severity of thrombocytopenia and azotemia as well as scoring during pregnancy can serve as a guide, but not as a defining feature of the diagnosis.The key to the differential diagnosis is the effect of delivery on the regression of TMA: if hemolysis and thrombocytopenia decrease after delivery, one can speak of ‘pure’ pre-eclampsia (PE) or HELLP-syndrome. If persistent or increasing, thrombotic thrombocytopenic purpura (TTP) and aHUS should be considered. With an ADAMTS 13 level of less than 10%, a diagnosis of TTP is made. With ADAMTS 13 over 10-20%, the patient falls into the «grey zone» and a repeat enzyme test is required. If there are signs of fulminant multiple organ failure, especially in a patient with initial suspicion of APS, CAPS can be suspected. To confirm it, high titres of APA are required. In addition, TMA may cause: sepsis and various urgent obstetric conditions complicated by the development of DIC.