Evaluation and management of upper urinary tract obstruction in infancy and childhood.

Our clinical experience over the past 5 years would suggest that both the diuretic renogram and the Whitaker study permit an objective and quantitative assessment of urinary obstruction. The diagnostic accuracy of both studies exceeds 90 per cent, although neither study has proved to be infallible. Both have potential sources of error that must be monitored carefully if their reliability is to be maximized. Potential sources of error in the diuretic renogram include the state of hydration, renal functional status, distensibility and volume of the collecting system, a filled bladder, and ability to respond to the diuretic. Its reliability can be increased if the standard testing protocol is followed, the study closely monitored, and the limitations of the test realized. Interpretation of the diuretic renogram based only upon the appearance of the washout curve without consideration of the calculated half time or the sequential analogue images is unreliable and in our experience would have been responsible for an incorrect interpretation in 40 per cent of patients. The diuretic renal scan is used as the initial testing modality because it is reliable, reproducible, noninvasive, and objective and provides important information concerning individual renal function. Over 80 per cent of children with hydronephrosis can be completely evaluated by the diuretic renogram alone without the need for more invasive testing modalities. Nevertheless, the pressure perfusion study will continue to be necessary for the evaluation of certain individuals. Because of its invasive nature, we prefer to reserve this study for very specific, well-defined circumstances.(ABSTRACT TRUNCATED AT 250 WORDS)