Question category: Haematology
A 12 year old girl presents with profuse diarrhoea. It was initially watery and then became bloody. She was unwell with fever, abdominal pain, petechial rash and vomiting. Bloods reveal a low haemoglobin with elevated reticulocytes, LDH and bilirubin, low platelets and acute renal failure. Coombs test is negative. What is the most likely diagnosis?