Urine Dipstick Test for the Diagnosis of Urinary Tract Infection

A systematic review 2 examined the use of urine leukocyte esterase and nitrite tests in adults to exclude or rule out urinary tract infection (UTI). 23 trials, which used a cut-off of 108 colony-forming units per liter, were combined in a meta-analysis. The leukocyte esterase or nitrite test combination, with one or the other test positive, was used in 14 studies, showed the highest sensitivity and the lowest negative likelihood ratio. While there was significant heterogeneity between the studies, 7 of 14 demonstrated significant decreases in pretest to posttest probability with a pooled posttest probability of 5% for the negative result. In certain circumstances, there is evidence for the use of urinalysis as a rule-out test for UTI.

A cross-sectional study 3 included 616 consecutively enrolled participants suspected of having a urinary tract infection. The optimal test characteristics were obtained when index test positivity was defined as any leucocyte esterase reaction and/or a nitrite reaction and reference test positivity was defined as a urine culture with a growth of at least 103 colony-forming units/mL (sensitivity: 88.2% (95% CI 81.6 to 93.1), negative predictive value: 93.0% (95% CI 88.9 to 95.9)). The post-test probability of a positive urine culture after a negative urinary dipstick test was 7% in the obstetric/gynaecology clinic and 8% in the internal medicine clinic.

A cross-sectional study 4 included 359 patients. 252 patients were culture positive, White blood cell (WBC) sensitivity and specificity were 62.7% and 100%, and nitrite sensitivity and specificity were 20.6% and 93.5%, respectively. 99 diabetic patients were culture positive; for diabetic patients, WBC sensitivity and specificity were 65.7% and 100% and nitrite sensitivity and specificity were 18.2% and 97.6%, respectively, while for non-diabetic patients, WBC sensitivity and specificity were 60.85% and 100% and nitrite sensitivity and specificity were 22.2% and 90.8%, respectively.

Comment: The quality of evidence is downgraded by heterogeneity (wide range of reported results).

References

• St John A, Boyd JC, Lowes AJ et al. The use of urinary dipstick tests to exclude urinary tract infection: a systematic review of the literature. Am J Clin Pathol 2006;126(3):428-36. [PubMed]
• Ginting F, Sugianli AK, Kusumawati RL et al. Predictive value of the urinary dipstick test in the management of patients with urinary tract infection-associated symptoms in primary care in Indonesia: a cross-sectional study. BMJ Open 2018;8(8):e023051. [PubMed]
• Mohanna AT, Alshamrani KM, SaemAldahar MA et al. The Sensitivity and Specificity of White Blood Cells and Nitrite in Dipstick Urinalysis in Association With Urine Culture in Detecting Infection in Adults From October 2016 to October 2019 at King Abdulaziz Medical City. Cureus 2021;13(6):e15436. [PubMed]