Factors Related to Thrombotic Microangiopathies in Pregnancy: Integrative Review

Abstract

Introduction: Pregnancy is a state that can precipitate the occurrence of a thrombotic microangiopathy (TMA), characterized by the presence of microangiopathic hemolytic anemia and the existence of thrombi in the microcirculation. Conditions not very common, but that determine high maternal and fetal morbidity and mortality, as Hemolytic Uremic Syndrome (HUS), Thrombotic Thrombocytopenic Purpura (TTP) and Hemolysis Elevated Liver Enzymes, and Low Platelet Count (HELLP) syndrome.Objective: Identifying factors related to the occurrence of thrombotic microangiopathy in pregnancy, based on the analysis of scientific production.Method: An integrative review of literature, using the descriptors thrombotic microangiopathy, pregnancy, thrombotic microangiopathy, pregnancy; the consulted databases were PubMed, LILACS and SciELo with six articles published between 2003 and August 2014. The results were shown in summary frames.Results: Evidence points to the failure in the cleavage of multimers of von Willebrand factor (FvW), due to deficiency of plasma metalloprotease ADAMTS13 in TTP; endothelial activation as responsible for hemolytic thrombotic state, which occurs in the diathesis gravidarum HELLP syndrome and the alternative pathway of complement dysregulation involved in atypical aspect of the HUS are the main IntroductionPregnancy is a period of the life cycle characterized by physiological changes of the maternal organism, ranging from structural and anatomical changes to functional changes in various organs and systems [1]. Nevertheless, many pathological conditions may be secondary or exacerbated by pregnancy, such as thrombotic microangiopathy (TMA) and Hemolysis Elevated Liver Enzymes, and Low Platelet Count (HELLP) syndrome, not very common conditions but which determine high maternal and fetal morbidity and mortality [2].The TMA is characterized by the presence of microangiopathic hemolytic anemia and the existence of thrombi, compounds, mostly by fibrin and platelets in the microcirculation of various organs, especially the brain and kidney. There may be swelling of endothelial cells, with accumulation of cellular debris and proteins in subendothelial layer, causing a detachment of the cell basement membrane [3].HELLP syndrome, characterized by microangiopathic hemolysis, thrombocytopenia and elevated liver enzymes, is a likely serious complication of pre-eclampsia, which determines kidney damage, brain, liver and placenta at different levels depending on the degree of microangiopathic lesions [2]. This syndrome is also considered an TMA in which fibrin thrombi are evident in liver biopsies, in affected patients [4].The pathophysiology of HELLP syndrome is not yet fully elucidated. Disorders including this syndrome, thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS) and acute fatty liver of pregnancy (AFLP) have been proposed as spectrum of the same disease process. The common pathophysiologic link seems to injury/endothelial dysfunction with consequent vasospasm, activation-a...