Abstract
Stones are the most common cause of collecting system ruptures. There are few reported cases of a ruptured collecting system without an underlying pathological cause. We report a case of a 15-year-old female patient who presented with left flank pain that was associated with nausea and vomiting. Computed tomography revealed a large, left retroperitoneal fluid collection, which was associated with severe hydronephrosis without an obvious pathological cause. The patient was treated with the insertion of a left double-J stent, and a retrograde pyelography confirmed the cessation of extravasation. At follow up, she was treated surgically with left robotic-assisted pyeloplasty without complications.