Warm or cold contrast medium in the micturating cystourethrogram (MCUG): which is best?

The purpose of this study was to determine what difference using room temperature ("cold") or body temperature ("warm") contrast medium had on the outcome of MCUG examinations in infants under 1 year of age.

One hundred infants (50 males and 50 females) referred for an MCUG were identified. Individuals with known bladder neuropathy were excluded. Each was randomized to receive either warm or cold contrast medium. The screening time, volume of contrast instilled, number of attempts at voiding, patient distress, completeness of bladder emptying and incidence of reflux were measured and the results between the two groups compared.

No difference was found between the two groups with regards to screening time, volume of contrast instilled or number of attempts at voiding. There was a statistically significant (p<0.05, chi square) difference in distress levels, with more children crying during instillation of cold contrast medium than warm. Bladder emptying was more often to completion when using cold contrast medium (32 compared with 16%), and vesicoureteric reflux (VUR) was more commonly demonstrated when using warm contrast medium (16 compared with 6%), although these values did not reach statistical significance.

Warm contrast medium causes significantly less distress than cold contrast medium, but does not prolong screening time or increase the volume of contrast required.