Pregnancy-Associated Atypical Hemolytic Uremic Syndrome: A Systematic Review

To evaluate disease presentation, diagnosis, treatment, and clinical outcomes in pregnancy-associated atypical hemolytic uremic syndrome (aHUS). DATA SOURCES: We searched PubMed, MEDLINE, Cochrane Library, ClinicalTrials.gov, Web of Science, EMBASE and Google Scholar, from inception until March 2018. METHODS OF STUDY SELECTION: We included English-language articles describing aHUS in pregnancy or postpartum. The diagnosis of aHUS was characterized by hemolysis, thrombocytopenia, and renal failure and was distinguished from typical diarrhea-associated hemolytic uremic syndrome. Patients were excluded if individual data could not be obtained, the diagnosis was unclear, or an alternative etiology was more likely, such as thrombotic thrombocytopenic purpura or Shiga toxin–producing Escherichia coli. Reports were appraised by two reviewers, with disagreements adjudicated by a third reviewer. TABULATION, INTEGRATION, AND RESULTS: The search identified 796 articles. After review of titles, abstracts, and full text, we identified 48 reports describing 60 unique cases of pregnancy-associated aHUS, with 66 pregnancies. Twelve cases involved pregnancy in women with known aHUS, and 54 cases involved first-episode pregnancy-associated aHUS. Women with known aHUS, particularly those with baseline creatinine at or above 1.5 mg/dL, had a high rate of adverse pregnancy outcomes. For first-episode pregnancy-associated aHUS, diagnosis most often occurred postpartum (94%), after a cesarean delivery (70%), in nulliparous women (58%). Preceding obstetric complications were common and included fetal death, preeclampsia, and hemorrhage. Diagnosis was usually made clinically, based on the triad of microangiopathic hemolysis, thrombocytopenia, and renal failure. Additional testing included renal biopsy, complement genetic testing, and ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) testing. Treatment modalities included corticosteroids, plasma exchange, dialysis, and eculizumab. More women with first-episode pregnancy-associated aHUS achieved disease remission when treated with eculizumab, compared with those not treated with eculizumab (88% vs 57%, P=.02). CONCLUSION: Pregnancy-associated aHUS usually presents in the postpartum period, often after a pregnancy complication, and eculizumab is effective for achieving disease remission. SYSTEMATIC REVIEW REGISTRATION: PROSPERO, CRD42019129266.