Clinical bottom line
Combined evidence indicates that urethral catheter samples are more likely to be contaminated than samples obtained by suprapubic aspiration (Grade C) but not all evidence is of high quality .
Catheter sample contamination can be reduced by culturing the second half of the sample only ( Grade B).
Catheter samples may still be more appropriate than suprapubic aspiration (number needed to harm (NNH 9) where it is felt there is higher chance of success influenced by clinical factors such
as age, the size of the baby, other co- morbidities and potentially parental preference.
Source : Arch Dis Child September 2009 Vol 94 No 9 page 736