Purpose or Case Report: Hemolytic uremic syndrome (HUS) is a recognized but still uncommon disease with an incidence varying between 1 to 3 cases per 100,000 annually. It consists of a triad of acute renal failure, microangiopathic hemolytic anemia, and thrombocytopenia, with this triad resulting from endothelial cell damage, intravascular hemolysis, platelet activation, and subsequent microthrombi with multi-organ involvement.

Classical cases involve a school age child with diarrhea with diarrhea and acute renal failure. This form of HUS is post-infectious from exposure to a Shigella toxin-producing E. coli (STEC) and was previously called typical HUS. A newer understanding of the condition and pathophysiology has brought about changes into the classification, which the radiologist should be aware of. HUS can now be best divided into:

- Hereditary HUS (where there are gene-related changes affecting the body’s coagulation regulation)
- Acquired HUS, which can be post-infectious (as in STEC, pneumoccous, HIV), from autoantibodies or drug-related.

As understanding of the condition has changed, this review aims to bring the imaging features in line for hereditary HUS and acquired HUS. This cross-center educational review will focus on multi-modality and multi-system imaging findings, which have typical features on ultrasound, CT and MRI. It will also highlight differences that occur in the presentation and findings in three large centers that are positioned in different parts of the world. We will focus on early recognition to aid the clinician; however, we will also detail the significant complications in the genitourinary, gastrointestinal, and central nervous systems that can occur.

Learning Points:
- Understand the evolution of HUS classification and appreciation of how this is important for the radiologist to aid diagnosis.
- Learn the imaging findings in classical HUS as well as the rarer forms of HUS, in addition to how these conditions present across different countries.
- Appreciation of the use of multimodality imaging to facilitate earlier detection to aid the clinician and child with earlier diagnosis.
- Recognition of the multisystem organ involvement and complications associated with HUS.
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