RESUMEN
BACKGROUND: Spontaneous formation of urinoma is a rare condition, especially for pregnant women. We report a patient in the third trimester of pregnancy with a spontaneous renal rupture who then develops a urinoma from urine leaking into the perinephric space. CASE PRESENTATION: A 23-year-old primagravida was diagnosed with a spontaneous renal rupture and acute left loin pain accompanied by hematuria when she was 35 weeks pregnant. A sub-capsular perinephric cyst then developed to a size of 319 × 175 × 253 mm, and because of discomfort to the patient, we performed Cesarean section. After a healthy male newborn was delivered, fluid was suctioned from a large perirenal cyst that had an estimated size of 300 × 200 × 300 mm. A percutaneous nephrostomy tube was left in the cyst until CT showed no remaining fluid. In the six-month follow-up, the patient showed no perirenal extravasation according to an ultrasound scan, and the urine analysis and renal function tests were normal. CONCLUSION: Close follow-up should be recommended for the patient who has renal rupture after conservative therapy, especially for pregnant woman. CT or MRI should be considered in addition to utilizing ultrasound in the management of pregnant women who present with urinomas. Percutaneous nephrostomy is suggested as an appropriate treatment for large urinomas.