Flushing of the vagina and the prepuce-a cause for contaminated urine cultures in children.

ABSTRACT

OBJECTIVE: An uncontaminated urine culture is a prerequisite for the diagnosis of a urinary tract infection. However, this may be difficult to obtain in small children. We have studied the frequency of ballooning of the prepuce in non-circumcised boys and vaginal reflux in girls during voiding as a possible cause of contaminated urine cultures. METHODS: All micturating cystourethrograms (MCUG) performed in our institution over the last 5 years in children aged 0-15 years were reviewed retrospectively for ballooning of the foreskin or vaginal reflux as a potential source of bacterial contamination. The voiding pictures were routinely done with the catheter present for the first voiding cycle and then removed on the second void. RESULTS: A total of 526 children (77.4 % boys, 22.6 % girls) were eligible for the study. Ballooning of the foreskin was identified on the micturition pictures of 115 (38 %) boys, with the frequency significantly higher in boys aged <12 months [odds ratio (OR) 4.1; 95 % confidence interval (CI) 2.1-7.3)] and boys with vesicoureteral reflux (OR 1.6; 95 % CI 1.06-2.4). Seventeen girls (14.3 %) showed vaginal reflux. No correlation with age or vesicoureteral reflux was found in the girls. CONCLUSION: Ballooning of the prepuce or vaginal reflux was seen on a fluoroscopic MCUG in a large proportion of children during their voiding. This normal phenomenon might cause contaminated urine cultures when the urine is obtained by bag or clean catch.