The forgotten factor in the evaluation of vesicoureteric reflux

Vesicoureteric reflux is an important factor in pyelonephritic scar formation, but the radiological demonstration of reflux is often difficult. The influence rate of urine formation on radiological assessment of vesicoureteric reflux was studied in 21 patients. After an intravenous injection of 20 mg of frusemide, reflux was reduced or abolished in 19 of the 21 patients. In three patients, vesicoureteric reflux had not been demonstrated at an earlier examination under conditions of normal hydration, but cystourethrograms in the dehydrated state demonstrated reflux. Hydration is an important factor in assessing both the presence and degree of vesicoureteric reflux, and the incidence of false-negative results is reduced by preliminary fluid restriction. Decisions about whether reflux should be corrected surgically are usually based on the degree of reflux. Standardization of the rate of urine formation during micturating cystourethrography is therefore essential.