Urine cultures for kids

I thank Kolk for her request for clarification. Suppose you are seeing a 1-year-old infant who has had a fever for two days but whose results of physical examination are unremarkable. The pretest probability of urinary tract infection is about 20%.¹ My preference would be to obtain a catheter specimen for both urinalysis and culture.

If, however, the parents are strongly opposed to catheterization or obtaining a catheter specimen is not feasible, a bag urine specimen can be used to guide further management. If the dip-stick from the urine bag specimen gives negative results for both leukocytes and nitrites, the probability of urinary tract infection in this child would be < 5%.¹ The child can be followed up without any additional testing. If the results are positive, a catheter specimen should be obtained for urinalysis and culture.

With the extra time and effort involved in obtaining a repeat catheter specimen from the large number of children with positive results of bag urine analysis, we do not routinely use bags to collect urine. In our outpatient practice of > 25 000 patients, we use bags to collect urine samples for only a few patients each year.