Complement-Mediated Thrombotic Microangiopathy in Pregnancy: An Educational Case Report

• Published in: Canadian journal of kidney health and disease 2023, Vol.10, p.20543581231209009-20543581231209009
• Main Authors: Bruno, Valentina, Barth, David, Jauhal, Arenn
• Format: Report
• Language: English
• ISSN: 2054-3581; 2054-3581
• DOI: 10.1177/20543581231209009

RationaleThrombotic microangiopathy (TMA) is a spectrum of rare diseases characterized by thrombocytopenia, microangiopathic hemolytic anemia, and organ damage. Differentiating pre-eclampsia, HELLP (Hemolysis, Elevated Liver enzymes, Low Platelets) syndrome and atypical hemolytic uremic syndrome (aHUS) during pregnancy may be diagnostically challenging yet important as the treatment pathways differ. Most cases of aHUS are associated with dysregulation of the complement alternative pathway, for which current guidelines recommend prompt treatment with complement C5 inhibitor to prevent chronic sequelae. Here, we report a case of pregnancy-associated aHUS (p-aHUS) to highlight the challenging aspects of the diagnostic process and the importance of prompt treatment with complement inhibition to reduce the risk of poor outcomes.Presenting concernsA 28-year-old woman was admitted to a local hospital for induction of vaginal delivery of twins at 34 weeks and 3 days of gestational age, due to intrauterine growth restriction (IUGR). She was previously healthy, and this current pregnancy was uncomplicated, except for the IUGR. Approximately, 10 hours after her induced delivery, she developed vomiting, epigastric pain, and hypertension.DiagnosisShe was initially suspected of having fulminant liver failure in the context of acute fatty liver of pregnancy versus pre-eclampsia/HELLP syndrome, due to evidence of elevated liver enzymes, acute kidney injury (AKI), thrombocytopenia, and hemoglobin levels trending down, for which the patient was initially treated conservatively. On day 2 post-delivery, she was transferred to our hospital for possible liver biopsy and management of liver failure. Upon transfer, dialysis was started due to anuric AKI; at the same time, her liver function spontaneously improved, while platelet count remained very low and hemoglobin levels continued to trend down. A full TMA work-up revealed low C3 levels; secondary causes of TMA were ruled out. The patient received a final diagnosis of p-aHUS. Complement genetic tests were also performed and did not identify any pathogenic variants.InterventionsGiven the final diagnosis of p-aHUS, the patient was started on a C5 inhibitor (day 8 post-delivery). Her platelet count quickly normalized 2 days after the first dose, while the hemoglobin levels remained low for a longer period, likely due to retained products of conception.OutcomesThe patient was able to completely discontinue dialysis after approxima