Procedure Guideline for Diuretic Renography in Children 3.0*

Hydronephrosis (distension of the pelvicalyceal system) is one of the most common indications for radionuclide evaluation of the kidneys in pediatrie patients. The etiology of the hydronephrosis can be an obstructed renal pelvis, an obstructed ureter, vesicoureteral reflux, the bladder itself or the bladder outlet, infection or congenital in nature. Contrast intravenous urography, ultrasonography and con ventional radionuclide renography cannot reliably differentiate obstructive from nonobstructive causes of hydronephrosis and hydroureteronephrosis (distension of the pelvicalyceal system and ureter). The pressure perfusion study (Whitaker test), which mea sures collecting system pressure under conditions of increased pelvic infusion is relatively invasive. The evaluation of function in the presence of obstruction does not give reliable indication of potential for recovery following surgical correction. High pressure in the collecting system results in reduction of renal blood flow and function. The most common cause of unilateral obstruction is the presence of a ureteropelvic obstruction. Obstructions can also occur more distally at the ureterovesical junction. Bilateral hydronephrosis can be produced by posterior urethral valves, bilateral ureteropelvic obstructions or even a full bladder. The purpose of diuretic renography is to differentiate a true obstruction from a dilated nonobstructed system (stasis) by serial imaging after intravenous administration of furosemide (Lasix).