Low Grade Pelviureteric Junction Obstruction with Normal Diuretic Renography

We report five patients with normal diuretic renograms who underwent Whitaker pressure perfusion testing. They were found to have normal pressure at low flow rates (2-4 ml/min) and an abnormally elevated pressure at high flow rates (8-10 ml/min). Because of persistent symptoms, two patients underwent surgery, while the other three have been followed up. Our findings indicate that a negative diuretic renogram in a well hydrated patient with good renal function may not rule out low grade obstruction. Renal pelvic perfusion at low flow rates as well as high flow rates is recommended to determine better the function of the pelviureteric junction.