Are true-negative nitrite results affected by a two-hour delay in dipstick/pad analysis of urine in incontinence pads?

Urine collection methods and dipstick testing in non-toilet-trained children

Urinary tract infection is a commonly occurring paediatric infection associated with significant morbidity. Diagnosis is challenging as symptoms are non-specific and definitive diagnosis requires an uncontaminated urine sample to be obtained. Common techniques for sampling in non-toilet-trained children include clean catch, bag, pad, in-out catheterisation and suprapubic aspiration. The pros and cons of each method are examined in detail in this review. They differ significantly in frequency of use, contamination rates and acceptability to parents and clinicians. National guidance of which to use differs significantly internationally. No method is clearly superior. For non-invasive testing, clean catch sampling has a lower likelihood of contamination and can be made more efficient through stimulation of voiding in younger children. In invasive testing, suprapubic aspiration gives a lower likelihood of contamination, a high success rate and a low complication rate, but is considered painful and is not preferred by parents. Urine dipstick testing is validated for ruling in or out UTI provided that leucocyte esterase (LE) and nitrite testing are used in combination.

Role of dipstick testing in the evaluation of urinary tract infection in nursing home residents

Among 101 nursing home residents with suspected urinary tract infection (UTI), we determined the negative predictive value of dipstick testing for leukocyte esterase and nitrite to be 100% (95% confidence interval, 74%-100%), compared with laboratory evidence of UTI (greater than 10 white blood cells/mm(3) on urinalysis and greater than 100,000 colony forming units/mL on urine culture). Nursing home dipstick testing effectively excluded the possibility of UTI.