Clinical scenario

A 20 year old student presents to the emergency department with a three day history of urinary frequency, dysuria, and lower abdominal pain. Examination is unremarkable and dipstick urine analysis is normal. You wonder whether normal dipstick urine analysis is sufficient to rule out a UTI or whether antibiotics anyway should be prescribed whatever the result.

Three part question

In [adults with symptoms of a urinary tract infection] does [negative dipstick urine analysis] rule out a [UTI]?

Search strategy

Medline 1966–04/03 using the OVID interface. [(exp Urinalysis OR exp Indicators and Reagents OR exp Reagent Strips OR stix.af OR urinalysis.af) AND (exp Urinary Tract Infections OR (urin$ adj5 infect$).af OR UTI.af OR exp Bacteriuria OR bacteriur$.af) AND (dysuria.af OR frequency.af OR haematuria.af OR hematuria.af OR stranguria.af OR urgency.af)] LIMIT to human AND English language AND all adult <19 plus years>

Search outcome

Altogether 75 papers were found. Of these, two were identified as answering the three part question. One of these was a meta-analysis containing nine papers not identified by the original search as they did not consider dipstick urine analysis (table 1).

Comment(s)

The meta-analysis shows that the prevalence of UTI in patients who present with symptoms of UTI is around 50%. The probability of UTI is even higher (around 90%) with a convincing history. Dipstick urine analysis is a quick and inexpensive test however sensitivity (and therefore negative predictive value) were found to be as low as 75%. Some studies included in the meta-analysis were of low quality and further studies need to be done in this field.

CLINICAL BOTTOM LINE

Dipstick urine analysis is of insufficient sensitivity to be used to rule out UTI in patients with one or more symptoms.