- Patients will be excluded if they have diagnoses of typical HUS (diarrhea-associated HUS), atypical HUS, and disseminated intravascular coagulation, have abnormal INR at the time of presentation, have diagnoses of malignant hypertension at the time of presentation, are on the following drugs within 90 days prior to their presentation: ticlopidine, clopidogrel, mitomycin C, gemcitabine, cyclosporine, and quinine, have a history of hematopoietic stem cell transplantations prior to their presentation, have a history and/or diagnosis of vasculitis, systemic lupus erythematosus, scleroderma, rheumatoid arthritis, antiphospholipid antibody syndrome, or HIV/AIDS, have a history of solid organ malignancy within 5 years prior to presentation, i.e. lung, breast, gastric, colon, pancreatic, prostate, or liver, are pregnant at the time of presentation, have severe bronchospasm, unstable angina, and severe ischemic heart disease, have advanced kidney failure (estimated Glomerular Filtration Rate < 30 mL/min/1.73m2), and have history of allergic reaction to contrast dye.