The role of direct radionuclide cystography in evaluation of vesicoureteral reflux.

The validity of voiding cystourethrography (VCUG) for detecting vesicoureteral reflux in children and assessing its extent was compared with that of direct radionuclide cystography (DRNC). Of 131 patients with recurrent urinary tract infection, all underwent DRNC and most also VCUG. Vesicoureteral reflux was found at DRNC in nine renal units (9 patients) in which VCUG was negative. In 17 renal units (15 patients) VCUG showed reflux to the ureter, but not to the renal pelvis, whereas DRNC revealed backflow from the bladder up to the renal pelvis. Reflux visualized at DRNC but not at VCUG was defined as grade Io. In all cases with reflux of grade I according to current classifications, DRNC showed reflux up to the renal pelvis. These observations make the distinction between grades I and II reflux in presently used classification less relevant and indicated the possible pathway of renal infection in patients with grade I vesicoureteral reflux and in so-called "elusive" reflux. We propose the addition of an extra grade (Io) of vesicoureteral reflux.