Thrombotic microangiopathy (TMA) represents a heterogeneous group of disorders characterized by microvascular thrombosis and end-organ damage. Pregnancy-associated thrombotic microangiopathy (p-TMA) has emerged as a distinct clinical entity with unique diagnostic challenges. Identifying the specific form of p-TMA is critical for appropriate and timely management. This review offers a comprehensive overview of the various forms of thrombotic microangiopathies associated with pregnancy, highlighting our current understanding of their pathophysiology and the evolving landscape of diagnosis and treatment for each.© 2024 International Society of Nephrology. Published by Elsevier Inc.

        血栓性微血管病（thrombotic microangiopathy，TMA）是一组以微血管栓塞为病理特征的疾病。主要表现为微血管病性溶血性贫血、血小板减少、微循环血小板血栓引起神经系统、肾脏等器官受累［1］。经典的血栓性微血管病主要指血栓性血小板减少性紫癜（TTP）和溶血性尿毒综合征（HUS）。TTP和HUS均有溶血及肾脏受累的症状，且血浆置换可取得较好的疗效，两者之间的鉴别诊断较为困难，其病理变化均为内皮细胞损伤、微血管内血栓形成。近年来也有学者提出将两种疾病合称为TTP-HUS综合征。浏览更多请关注本刊微信公众号及当期杂志。

Atypical hemolytic uremic syndrome (aHUS) is a rare disease in which uncontrolled terminal complement activation leads to systemic thrombotic microangiopathy (TMA). Pregnancy can trigger aHUS and, without complement inhibition, many women with pregnancy-triggered aHUS (p-aHUS) progress to end-stage renal disease (ESRD) with a high risk of morbidity. Owing to relatively small patient numbers, published characterizations of p-aHUS have been limited, thus the Global aHUS Registry (NCT01522183, April 2012) provides a unique opportunity to analyze data from a large single cohort of women with p-aHUS.The demographics and clinical characteristics of women with p-aHUS (n = 51) were compared with those of women of childbearing age with aHUS and no identified trigger (non-p-aHUS, n = 397). Outcome evaluations, including renal survival according to time to ESRD, were compared for patients with and without eculizumab treatment (a complement C5 inhibitor) in both aHUS groups.Baseline demographics and clinical characteristics were broadly similar in both groups. The proportion of women with p-aHUS and non-p-aHUS with pathogenic variant(s) in complement genes and/or anti-complement factor H antibodies was similar (45% and 43%, respectively), as was the proportion with a family history of aHUS (12% and 13%, respectively). Eculizumab treatment led to significantly improved renal outcomes in women with aHUS, regardless of whether aHUS was triggered by pregnancy or not: adjusted hazard ratio for time to ESRD was 0.06 (p = 0.006) in the p-aHUS group and 0.20 (p < 0.0001) in the non-p-aHUS group.Findings from this study support the characterization of p-aHUS as a complement-mediated TMA.

Atypical hemolytic and uremic syndrome (aHUS) is a severe disease strongly associated with genetic abnormalities in the complement alternative pathway. In renal posttransplantation, few data are available on recurrence risk and graft outcome according to genetic background in aHUS patients. The aim of this study was to identify risk factors for recurrence and transplant outcome and, in particular, the role of complement gene abnormalities. We retrospectively studied 57 aHUS patients who had received 71 renal transplants. A mutation in complement gene was identified in 39 (68%), in factor H (CFH), factor I (CFI), membrane cofactor-protein (MCP), C3 and factor B (CFB). At 5 years, death-censored graft survival was 51%. Disease recurrence was associated with graft loss (p = 0.001). Mutations in complement genes were associated with higher risk of recurrence (p = 0.009). Patients with CFH or gain of function (C3, CFB) mutations had a highest risk of recurrence. M-TOR inhibitor was associated with significant risk of recurrence (p = 0.043) but not calcineurin inhibitor immunosuppressive treatment (p = 0.29). Preemptive plasmatherapy was associated with a trend to decrease recurrence (p = 0.07). Our study highlights that characterization of complement genetic abnormalities predicts the risk of recurrence-related graft loss and paves the way for future genetically based individualized prophylactic therapeutic strategies.© Copyright 2013 The American Society of Transplantation and the American Society of Transplant Surgeons.

The objective of this guideline is to provide healthcare professionals with clear, up‐to‐date and practical guidance on the management of thrombotic thrombocytopenic purpura (TTP) and related thrombotic microangiopathies (TMAs), including complement‐mediated haemolytic uraemic syndrome (CM HUS); these are defined by thrombocytopenia, microangiopathic haemolytic anaemia (MAHA) and small vessel thrombosis. Within England, all TTP cases should be managed within designated regional centres as per NHSE commissioning for highly specialised services.

Over the past few years, new information has emerged in the management of both immune thrombotic thrombocytopenic purpura (iTTP) and congenital (or hereditary) thrombotic thrombocytopenic purpura (cTTP).In March 2024, the International Society on Thrombosis and Haemostasis (ISTH) formed a multidisciplinary panel comprising hematologists, intensivists, nephrologists, pathologists, patient representatives, and a methodology team. The panel discussed all treatment questions related to thrombotic thrombocytopenic purpura (TTP) using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) method to appraise evidence and formulate recommendations.For patients with cTTP in remission, a new strong recommendation was issued for the use of recombinant ADAMTS-13 over fresh frozen plasma in the context of moderate certainty evidence. The panel also revised a previous recommendation and suggested using fresh frozen plasma over a watch-and-wait approach for patients with cTTP in remission based on very low certainty evidence should recombinant. The panel reviewed and referenced new publications supporting therapeutic efficacy, potential survival benefit, and cost considerations of adding caplacizumab to therapeutic plasma exchange, corticosteroids, and rituximab, but concluded that no change was warranted to the previous recommendations in the management of iTTP. Good practice statements on the concomitant use of antithrombotic agents were marginally modified.For patients with iTTP, no change to 2020's recommendations. For patients with cTTP, the panel supports ADAMTS-13 replacement. Where accessible, recombinant ADAMTS-13 provides the most favorable balance of benefits and risks. Otherwise, fresh frozen plasma may still be effective. Shared decision-making should include the benefits, the potential harms, and the burden of care.Copyright © 2025. Published by Elsevier Inc.

Thrombotic thrombocytopenic purpura (TTP) is not uncommonly seen in pregnancy, either with the first episode or with the exacerbation of known disease. The management of TTP in pregnancy can be challenging if there is refractoriness to the use of therapeutic plasma exchange (TPE) and high‐dose corticosteroids. Caplacizumab, a vWF‐directed humanized antibody fragment, is approved for the treatment of acquired TTP but there is sparse data on its use in pregnant patients. Antenatal and peripartum haemorrhage is a theoretical concern with the use of the medication in the obstetric population. However, as options for treatment of TTP in the patients who have refractory disease are significantly limited, off‐label use of caplacizumab to achieve disease control and prevent maternofetal morbidity and mortality is a reasonable consideration. This article described the successful use of caplacizumab in a pregnant patient with acquired TTP and the associated favourable outcome. The patient suffered an exacerbation following initial TPE and became refractory to both plasma exchange and high‐dose corticosteroids. Off‐label use of caplacizumab resulted in hematologic recovery and successful delivery of a healthy neonate. This case represents a contribution to the sparse literature on the use of this effective medication in an often‐challenging clinical situation.

Thrombotic microangiopathy (TMA) represents a heterogeneous group of disorders characterized by microvascular thrombosis and end-organ damage. Pregnancy-associated thrombotic microangiopathy (p-TMA) has emerged as a distinct clinical entity with unique diagnostic challenges. Identifying the specific form of p-TMA is critical for appropriate and timely management. This review offers a comprehensive overview of the various forms of thrombotic microangiopathies associated with pregnancy, highlighting our current understanding of their pathophysiology and the evolving landscape of diagnosis and treatment for each.© 2024 International Society of Nephrology. Published by Elsevier Inc.

Atypical hemolytic uremic syndrome is a complement-mediated thrombotic microangiopathy caused by uncontrolled activation of the alternative complement pathway in the setting of autoantibodies to or rare pathogenic genetic variants in complement proteins. Pregnancy may serve as a trigger and unmask atypical hemolytic uremic syndrome/complement-mediated thrombotic microangiopathy (aHUS/CM-TMA), which has severe, life-threatening consequences. It can be difficult to diagnose aHUS/CM-TMA in pregnancy due to overlapping clinical features with other thrombotic microangiopathy syndromes including hypertensive disorders of pregnancy. However, the distinction among thrombotic microangiopathy etiologies in pregnancy is important because each syndrome has specific disease management and treatment. In this narrative review, we discuss 2 cases to illustrate the diagnostic challenges and evolving approach in the management of pregnancy-associated aHUS/CM-TMA. The first case involves a 30-year-old woman presenting in the first trimester who was diagnosed with aHUS/CM-TMA and treated with eculizumab from 19 weeks' gestation. Genetic testing revealed a likely pathogenic variant in CFI. She successfully delivered a healthy infant at 30 weeks' gestation. In the second case, a 22-year-old woman developed severe postpartum HELLP syndrome, requiring hemodialysis. Her condition improved with supportive management, yet investigations assessing for aHUS/CM-TMA remained abnormal 6 months postpartum consistent with persistent complement activation but negative genetic testing. Through detailed case discussion describing tests assessing for placental health, fetal anatomy, complement activation, autoantibodies to complement regulatory proteins, and genetic testing for aHUS/CM-TMA, we describe how these results aided in the clinical diagnosis of pregnancy-associated aHUS/CM-TMA and assisted in guiding patient management, including the use of anticomplement therapy.Copyright © 2024 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.