Infected urinoma secondary to a ruptured renal calyx from a partial staghorn stone

A urinoma is a collection of urine outside the urinary tract as a result of disruption of the collecting system. Obstructive causes of urine extravasation secondary to stones are not unseen but display a delayed diagnosis due to the gradual onset of symptoms, which can mimic pyelonephritis. We present the case of a 70-year-old female patient who was admitted to hospital with symptoms of right loin pain and sepsis. We describe her case from the initial clinical diagnosis of pyelonephritis to the final diagnosis of an infected urinoma after a calyceal rupture from an obstructive partial staghorn calculus. This case highlights the importance of early computerized tomography imaging in patients with renal stones and suspected pyelonephritis as ultrasound scans can sometimes be misleading. Misdiagnosis of infected urinomas delays definitive treatment and leads to increased morbidity.