A 34-year-old man with an unremarkable medical history (except for surgical repair of an inguinal hernia several years ago) was referred to the emergency department because of sudden, severe, colicky pain in his back and right flank. Intramuscular injection with diclofenac 75 mg by his general practitioner had no effect on his symptoms. He used no medication, denied traumatic injury, and had no gastrointestinal complaints. At physical examination his blood pressure was 135/85 mmHg, pulse 80 beats per minute, and temperature 36.2° Celsius. Deep palpation of the abdomen, flank, and back was not painful. Laboratory tests revealed slightly elevated inflammatory parameters (i.e., C-reactive protein 49 mg/l, leukocyte count 11.4 x 109/l) and an elevated lactate dehydrogenase level of 783 U/l. Urine analysis showed microscopic haematuria (> 200 erythrocytes/µl). The patient was admitted to the urology ward under suspicion of urolithiasis. An abdominal ultrasound and abdominal X-ray, however, showed no abnormalities of the kidneys or urinary tract. Therefore, a computed tomography (CT) scan was performed (figure 1).