Rare manifestation of atypical hemolytic uremic syndrome in pregnancy: A case report

Atypical hemolytic uremic syndrome (aHUS) is a life-threatening thrombotic microangiopathy (TMA) driven by dysregulation of the alternative complement pathway. Within obstetrics, its diagnosis is critically confounded by profound clinical mimicry of common obstetrical emergencies. Delayed diagnosis is invariably associated with the rapid progression of multi-organ dysfunction syndrome (MODS), culminating in unacceptably high maternal and perinatal mortality and irreversible disability. This article presents a rare clinical case of aHUS triggered by placental abruption at 27 weeks of gestation in a patient with a history of two uncomplicated term deliveries. The initial clinical presentation was dominated by hemorrhagic shock and disseminated intravascular coagulation (DIC) secondary to massive abruption, which effectively masked the classic TMA triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. A systematic diagnostic workup including thromboelastography, schistocyte quantification, ADAMTS-13 activity assay, and renal biopsy was required to sequentially exclude other TMA subtypes and definitively establish the diagnosis. Despite a significant delay in initiating targeted therapy with the C5 complement inhibitor eculizumab and the development of severe acute kidney injury with cortical necrosis requiring prolonged renal replacement therapy (RRT), a favorable outcome was achieved. Eculizumab therapy facilitated gradual recovery of native renal function, culminating in the complete discontinuation of RRT. This case underscores placental abruption as a independent trigger for aHUS. It provides a compelling rationale for the inclusion of aHUS in the differential diagnosis of any complex obstetrical catastrophe and offers crucial clinical evidence supporting the potential for renal recovery following delayed initiation of complement blockade, even in the setting of severe, established parenchymal injury.

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