Vaillancourt S et al. (2007) To clean or not to clean: effect on contamination rates in midstream urine collections in toilet-trained children. Pediatrics 119: 1288–1293

Midstream urine specimens are used to diagnose urinary tract infections in children. Accurate diagnosis is essential to guarantee correct therapy and prevent unnecessary treatment and hospital admission in uninfected children. Vaillancourt and colleagues carried out the first randomized trial in toilet-trained children to investigate the effect of cleaning on bacterial contamination rates of midstream urine specimens.

Between 1st November 2004 and 1st October 2005, all toilet-trained children between the ages of 2 and 18 years who presented to the pediatric emergency department and required midstream urine sample were eligible for inclusion in the study. Parents were asked for consent and their children were then randomized to cleaning or not cleaning the perineum with soap at the start of each week. Intention-to-treat analysis was used to determine the risk of a contaminated urine culture and the risk for positive urinalysis.

In total, 350 children were enrolled in the study (211 girls and 139 boys). In the whole study population, the total prevalence of urinary tract infections was 7%. In the cleaning group the rate of contamination was 7.8% (14 of 179) versus 23.9% (41 of 171) in the noncleaning group. Children in the noncleaning group were more likely to have a positive urinalysis (36.8%; 63 of 171) than children in the cleaning group (20.6%: 37 of 179).

The authors recommend that before collecting a midstream urine sample, toilet-trained children should have their perineum cleaned with soap to reduce the risk of unnecessary treatment.