[Can the urine dipstick be used in the diagnosis of urinary bacterial colonizations in a preoperative urological assessment?].

PURPOSE: The use of the dipstick urinalysis has been validated for the diagnosis of symptomatic urinary infections, cystitis and pyelonephritis thanks to an excellent negative predictive value. For prostatitis, it is rather its positive predictive value that is interesting. The aim of this study is to validate its use in the screening of urinary colonizations in the preoperative assessment in urology.

METHODS

A monocentric prospective study was carried out for one year in 2011 comparing the data from the urine dipstick test with a fresh-voided midstream urinary examination and culture performed on the day of admission with the same urine sample in 598 asymptomatic patients programmed for a urological procedure. The gold standard to diagnose a microbiological-confirmed urinary tract infection or colonization was uropathogen growth of ≥10(3) colony-forming units per ml (cfu/mL) with or without leucocyturia.

RESULTS

The study disclosed 5% of colonized patients. The urine dipstick test had a 65% sensitivity and a 97% negative predictive value. However, the low sensitivity of the urine dipstick test entailed 34% of false negatives.

CONCLUSION

In spite of a good negative predictive value linked to a low prevalence of colonized patients (5%), the low sensitivity of the urine dipstick test entails a non-negligible number of false negatives. Its use as a single test of preoperative screening would expose colonized patients to the prospect of an operation, which seems to be unacceptable for some of them, notably endoscopic ones.

LEVEL OF EVIDENCE: 4.