Case Presentation: We present the case of a 31 year old primigravida African American woman who presented to her post-partum follow up clinic visit two weeks after Cesarean section delivery of a preterm live infant at 29 weeks. She was found to be in hypertensive emergency (220/120 mmHg), with complaints of acute diffuse abdominal pain, frontal headaches and new-onset bilateral leg swelling. Her pregnancy was complicated by premature ROM and chorioamnionitis. On examination, she was afebrile with normal mental status. She also had mild tenderness to palpation in all abdominal quadrants and 2+ pitting edema to the level of the knees bilaterally.Initial laboratory results revealed acute kidney injury (creatinine 2.5mg/dL), thrombocytopenia, hemolytic anemia with schistocytes on smear, markedly elevated LDH levels (>2000), and undetectable haptoglobin levels. Urinalysis was notable for active sediment with nephrotic range proteinuria and hematuria. Nephrology was consulted and she was promptly started on intravenous steroids with emergent plasmapheresis. Diagnosis of atypical hemolytic uremic syndrome (aHUS) was confirmed with normal ADAMTS-13 level. Hemodialysis was eventually initiated for worsening kidney function. She was started on Eculizumab after 48 hours. After two doses, hemoglobin and platelets improved with notable recovery of her kidney function. Genetic workup for identification of inherited complement abnormalities was unremarkable. The patient remains on ongoing eculizumab therapy and hemodialysis.
Discussion: Pregnancy-associated atypical hemolytic uremic syndrome (p-aHUS) is a rare condition caused by dysregulation of the complement system alternative pathway which tends to occur primarily in the post-partum period. Its incidence is estimated to be 1-2 cases per million population per year in the United States.
The three main features of aHUS are hemolytic anemia, thrombocytopenia, and acute kidney failure, however clinicians must be aware that not all patients present with the three classic findings at the exact time. There have been published cases of patients having only one or two presenting symptoms with eventual confirmed diagnosis of aHUS. It is a challenging condition that could easily be mistaken for other well-known postpartum complications such as preeclampsia and HELLP syndrome leading to delay in treatment. Eculizumab, a humanized anti-C5 monoclonal antibody to inhibit complement-mediated thrombotic microangiopathy, is the mainstay of treatment for aHUS.
In this presenting case, although the patient’s first pregnancy was the cause of her illness, it is important to note that aHUS may also be triggered by other more common causes known as complement-amplifying conditions (CACs) such as infection, transplantation, malignancy, hypertensive emergency, drugs and autoimmune conditions.
Conclusions: It is very important for clinicians to be vigilant, promptly recognize, diagnose and treat this ultra rare disease to avoid complications including end stage renal disease and possibly death that could result if early diagnosis is not made.