Urethral catheter or suprapubic aspiration to reduce contamination of urine samples in young children?

You are the paediatric senior house office running the prolonged jaundice clinic. A urine sample from a baby was collected via the “clean catch” method and has a mixed (contaminated) growth on culture. You need to recall the baby for repeat urine culture and wonder whether it is best to perform a suprapubic aspiration to minimise the chance of another contaminated sample or whether an in–out urethral catheter sample would be as good.

Structured clinical question

In non-toilet-trained children [population] is urethral catheterisation as good as suprapubic aspiration [intervention] at obtaining uncontaminated urine samples [outcome] and so detecting true urinary tract infections?

Search strategy

Primary source

Medline via PubMed was the primary source of articles. Search terms: catheter* AND suprapubic AND (urine OR urinary). Limits were: human, English language and ages 0–5 years. Dates included 1966 to September 2008. An initial search for direct comparisons was undertaken, and because of the low numbers of studies, all papers which compared suprapubic aspiration or urethral catheterisation with clean catch urine samples were also included.

Secondary sources

Secondary searches on the Cochrane database, Clinical Evidence and SUMsearch were performed using the same search terms.

Search outcome

A total of 123 papers were found via PubMed. Studies not comparing suprapubic aspiration and urethral catheter samples were excluded, as were any that did not have culture result as an outcome. This left two relevant direct comparison papers. The references of the above papers were checked, along with the linked articles, and one further article was found (which dated from before 1966).

An additional six articles were found comparing suprapubic aspiration or urethral catheterisation with clean catch sampling. Clean catch was chosen as the comparator as it is the first line collection method recommended by the National Institute for Health and Clinical Excellence (NICE).