Routine urine culture (once a month) is often performed as part of the follow-up of children with congenital nephro-urological malformations or as part of the standard screening tests for children in good clinical condition. In these cases, the finding of bacterial growth, even at high colony counts, is almost certainly due to contamination, given the difficulty involved in collecting a sterile specimen from a child, or the possible presence of asymptomatic bacteriuria, which does not require specific treatment. Bag urine collection, a method widely used in children for the collection of a suitable specimen for urine culture, carries a high risk of contamination and should be replaced by other methods such as the mid-stream clean catch method or urinary catheterisation.