Imaging of uretero-pelvic junction obstruction with stimulated diuresis. With consideration of the reliability of ultrasonography.

Eighty-nine kidneys of 81 infants and children with uretero-pelvic junction obstruction were investigated using ultrasonography (US), diuretic urography (DUR) and diuretic renography (DREN). Results of the US were false-negative in 14%. This can be avoided by ensuring that the patients get an amount of fluid appropriate to their age before the examination or by performing diuretic ultrasonography with frusemide. False-positive results were found with US in 15%, but obstruction was excluded by using the DUR and/or the DREN. During post-operative follow up the DUS is useful and after 6 months the clearance with 123-iodine hippurate combined with the DREN should be performed. The performance of the Whitaker-test is unnecessary.