A 52-year-old man presents with right-sided flank pain for three hours. The pain started suddenly while he was at rest, is constant, and is described as 10/10 in intensity. He also vomited twice. There is no history of chest pain, dyspnea, fever, or bladder or bowel dysfunction. His medical, surgical, and drug histories are unremarkable. He has no known allergies. He drinks socially and does not smoke. There is no history of recreational drug use.

The intensity of the pain decreases to 8/10 after administration of NSAIDs and morphine. An ECG and full blood count are normal. A urinalysis is positive for microscopic hematuria. There are no pus cells, and the nitrite and leukocyte esterase dipstick tests are negative.