Use of diuretic renogram in evaluation of patients before and after endopyelotomy.

OBJECTIVES: Endopyelotomy is a widely accepted alternative in the treatment of ureteropelvic junction (UPJ) obstruction, with success rates between 63% and 88%. However, various methods have been used to evaluate patients with UPJ obstruction, making it difficult to compare results. Diuretic renography has the potential to unify the evaluation if performed in standard ways. In this report, we present a standardized protocol for diuretic renography.

METHODS: Nineteen endopyelotomies were performed by one surgeon (E.B.K.) at our institution. The 16 patients were evaluated with technetium 99m MAG-3 diuretic renography. The presence or absence of obstruction was classified according to the differential renal function, time activity curves, and Tmax to T 1/2max time. Three patients had a postoperative Whitaker's test.

RESULTS: Eight patients had pre- and postoperative diuretic renograms at our institution. This group was stratified by their differential renal function. Among 4 patients with differential renal function greater than 35%, 3 of 4 showed progressive improvement in renal function postoperatively, 4 of 4 had a Tmax to T 1/2max time less than 10 minutes, and 3 of 4 ha d unobstructed time activity curves. Five patients had postoperative renograms only. Of these 5 patients, 4 had differential renal function greater than 35% and 3 of 5 had normal-appearing curves and normal Tmax to T 1/2max time. Three patients required a second endopyelotomy and 2 of these underwent a dismembered pyeloplasty.

CONCLUSIONS: Standardized diuretic renography should be used as an objective test for the evaluation of patients with UPJ obstruction. The successful outcome of an endopyelotomy depends on the preoperative renal function of the involved kidney. Whitaker's test may be used for equivocal cases.