Urine Contamination in Nontoilet-trained and Uncircumcised Boys

To assess any differences between the initial and midstream urine samples from nontoilet-trained, uncircumcised boys. Contamination during urine collection makes the diagnosis of urinary tract infections (UTIs) difficult in nontoilet-trained children, especially in uncircumcised boys. Whether the contamination comes mainly from the initial stream or the contact between urine and perineal skin is not known in this population.

A prospective diagnostic study between early and midstream urine samples was conducted on asymptomatic patients with no suspicion of UTI. The clean void method was performed in nontoilet-trained boys under general anesthesia. The exclusion criteria were circumcision, older than 3 years of age, recent antibiotics treatment, and recent UTI. Urinalysis and urine culture were performed, allowing a comparison between early and midstream urine samples.

Forty-four patients were enrolled in the study, and 31 satisfactory samples were obtained. A higher contamination rate was found in the early stream (n = 16; 51%) than in the midstream (n = 5; 16%) (P < .01). The positive culture from the early stream sample was statistically associated with a lower age (P = .02). The contamination rate of the first stream is 3-fold higher than for the midstream when collecting urine for urine culture.

The clean void method in nontoilet-trained, uncircumcised boys provides low-quality urine samples for both early and midstream urine samples. The benefit of catching midstream urine samples for the diagnosis of UTI in this population is even more important when the children are young.