Detection of Urinary Tract Infection (UTI) and Asymptomatic Bacteriuria using Urinalysis Parameters, a Review

Abstract

Background:Urinary tract infections (UTIs) are a very common occurrence globally. In order to diagnose a UTI accurately, one must be aware of the variable presentations of a UTI. Given this, UTIs generally have three presentations: Asymptomatic bacteriuria (ASB), acute cystitis, and pyelonephritis. Due to the pathology of UTIs, it is not uncommon to see significant bacteriuria in asymptomatic patients. Since UTIs are common, readily available means of diagnosis which are accurate and cost effective are needed. Therefore, urinalysis is regularly used in the diagnosis of UTI and ASB in pregnancy because they are easy to perform and produce results rapidly. However, there appears to be little evidence of their accuracy and cost-effectiveness as compared with standard culture techniques when quantified for positive and negative likelihood ratios. This is a literature review of the efficacy of urinalysis screening in the diagnosis of asymptomatic bacteriuria or UTI in pregnancy. Objective: The sensitivity and accuracy of urinanalysis parameters in detecting UTIs and Asymptomatic Bacteriuria during pregnancy was reviewed. This was done in order to evaluate the accuracy of nitrite and Leucocyte Esterase (LE) dipsticks for screening and treating UTIs and ASB in situations where culture results were not available. Conclusion: Overall, this review demonstrates that the urine dipstick test alone seems to be useful in to exclude the presence of an infection if the results of both nitrites and leukocyte-esterase are negative. Different studies reported broad ranges of sensitivities and specificities for urinalysis parameters. Combination of nitrite and leukocyte esterase when both parameters are positive, seem to have the highest specificity in detecting bacteriuria in asymptomatic pregnant women. Although the combination of positive test results are very sensitive in practice, the usefulness of the dipstick test alone to rule in an infection still remains doubtful, even with high pre-test probabilities. Urine culture remains the gold standard for diagnosis of urinary tract infection and asymptomatic bacteruria.