Gastroenterology and Hepatologymiddle twist
A 61-year-old man is brought to the emergency department after fainting and passing a large amount of bright red blood. His blood pressure is now 102/70 mmHg after resuscitation; he has no abdominal pain, and rectal examination reveals no palpable lesion. The blood urea concentration is 18 mmol/L (reference range 2.5–7.8) with a creatinine concentration of 82 micromol/L (reference range 60–110). Which one of the following is the most appropriate next investigation?