We report on a girl with infected perinephric urinoma and myelodysplasia who presented with a febrile urinary tract infection. A complex perinephric fluid collection with internal echoes was found on renal ultrasound, necessitating placement of a percutaneous drainage tube. Initial urodynamic testing after treatment of the infection revealed a noncompliant bladder with an elevated detrusor leak point pressure. Neurovesical dysfunction with elevated leak point pressure is believed to be the cause of urinoma. Clinical presentation, treatment and pathophysiology of this entity are discussed.