Accuracy of negative dipstick urinalysis in ruling out urinary tract infection in adults
Date First Published:
February 19, 2003
Last Updated:
July 1, 2003
Report by:
Nick Ohly, SHO (Manchester Royal Infirmary)
Search checked by:
Stewart Teece, Manchester Royal Infirmary
Three-Part Question:
In [adults with symptoms of a urinary tract infection] does [negative dipstick urinalysis] rule out a [UTI]?
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 urinalysis is normal. You wonder whether normal dipstick urinalysis is sufficient to rule out a UTI, or whether antibiotics anyway should be prescribed whatever the result.
Search Strategy:
Medline 1966-04/03 using the OVID interface.
Search Details:
[(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>
Outcome:
75 papers were found. Of these, 2 were identified as answering the three part question. One of these was a meta-analysis containing 9 papers not identified by the original search as they did not consider dipstick urinalysis.
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| Does this woman have an acute uncomplicated urinary tract infection? Bent S, Nallamothu BK, Simel DL et al. 2002, USA | Adult women from 9 original studies involving patients with symptoms of an UTI presenting to outpatient clinics. Total number of patients 2331 Positive dipstick defined as detectable nitrite or leukocyte esterase Prevalence 48% Gold standard of positive urine culture |
Meta-analysis | Sensitivity | 75% | Some studies only included women Only able to use data from some studies Difference in cut-off level for positive urine culture (range 100-100,000 CFU/ml) Some studies of poor quality |
| Likelihood of UTI in prescence of dysuria and frequency without vaginal discharge is high | >90% | ||||
| Comparison of test characteristics of urine dipstick and urinalysis at various test cutoff points. Lammers RL, Gibson S, Kovacs D et al. 2001, USA | 331 adult women presenting to ED or intermediate care centre with more than 1 symptom of a UTI Positive dipstick defined as detectable nitrite or leukocyte esterase Prevalence 45.9% Gold standard urine culture |
Prospective observational study | Sensitivity | 92% | Only women No sample size analysis |
| NPV | 83% |
Author Commentary:
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 urinalysis 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.
Bottom Line:
Dipstick urinalysis is of insufficient sensitivity to be used to rule out UTI in patients with one or more symptoms.
References:
- Bent S, Nallamothu BK, Simel DL et al.. Does this woman have an acute uncomplicated urinary tract infection?
- Lammers RL, Gibson S, Kovacs D et al.. Comparison of test characteristics of urine dipstick and urinalysis at various test cutoff points.