This case describes a 70-year-old female who presented with right flank pain around the site where a stent had been placed in her right kidney at an outside hospital several months earlier. The patient arrived tachycardic with a leukocytosis and a lactic acidosis. Further imaging revealed a very hydronephrotic right kidney and an extremely large fluid collection in the right retroperitoneum extending into the right flank consistent with leakage of urine from the obstructed right kidney. Prompt treatment of this rare phenomenon is crucial for delay in medical care can lead to abscess, hydronephrosis, electrolyte instability, and a progressive loss of renal function. Treatment for small urinomas is usually conservative as the collection will most often be reabsorbed. Larger urinomas even without systemic signs often necessitate more aggressive medical treatment. A drainage catheter can be placed with ultrasound or CT guidance. Percutaneous nephrostomy tubes are often used as well for additional drainage and decompression. Fluid culture is recommended to guide antibiotic treatment.