A more helpful techniqueBMJ 2000; 320 doi: http://dx.doi.org/10.1136/bmj.320.7231.377 (Published 05 February 2000) Cite this as: BMJ 2000;320:377
Urinary tract infection in young children is an easy diagnosis to miss not only because of its unusual mode of presentation but also because of the difficulty in the collection of a urine sample. It is reported that around 3-5% of girls and 1-2% of boys will have a symptomatic urinary tract infection in childhood. In children under 2 this may be due to a structural abnormality that may lead to permanent scarring and eventually to hypertension or renal failure.
Since Ahmad and colleagues published their paper on urine collection from disposable nappies, the position has been transformed dramatically.1 Gone are the sterile adhesive bags, which do not always stick properly to the skin, and in has come the 20 ml syringe from which the urine contents of the nappy can be squeezed into a specimen pot (provided highly absorbent brands containing gel beads are avoided from which it is impossible to extract any urine). As it is a much easier technique to use, it makes collection of urine by the parents more straightforward and so you are more likely to be able to exclude urine infection as a diagnosis in young children with a persistent high temperature or non-specific symptoms of feeding difficulties, vomiting, or diarrhoea—both of which are common clinical scenarios.
The good news is that urine cultures from urine obtained by the two methods give very similar results and that urine collection by padded disposable nappies, provided that they are not soiled and less than four hours old, is acceptable. If the urine is sterile we can be confident that we have excluded infection. The difficulty arises with an equivocal result—has this been due to contamination? In this instance I would refer to a paediatrician for a specialist assessment as I would with all apparent positive results to consider further investigation.
Apart from a few wry smiles from the parents, we have a cheaper and equally effective way of diagnosing urinary tract infections in young children.
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