Evaluation of the urinalysis and reagent strip testing to screen asymptomatic bacteriuria in pregnancy

Abstract

Objective To evaluate the diagnostic performance of the urinalysis and reagent strip testing as
a screening test for asymptomatic bacteriuria (ABU) in pregnant patients.
Study design Diagnostic test.
Material and Methods A clean-catch midstream urine specimen was evaluated in each of 392 pregnant
patients at the initial prenatal visit from January to June 2001. Simple urinalysis and reagent
strip tests were performed on all subjects. The presence of ³5 WBC/HPF of centrifuged urine
indicated a positive test for urinalysis, and the presence of either nitrites or leukocyte esterase
activity indicated a positive test for reagent strip test. ABU was defined as the presence of ³105
colony forming units of single bacteria per milliliter of urine. Sensitivity, specificity, positive
predictive value, and negative predictive value of the tests were calculated by using urine
culture as a gold standard.
Results The prevalence of ABU was 6.1%. The sensitivity and specificity of testing by urinalysis
were 41.7% and 68.5%, respectively. The reagent strip test offered a sensitivity of 66.7% and
a specificity of 51%. Combination of tests either in series or in parallel did not help improve
sensitivity over one of each.
Conclusion Neither test offers good sensitivity. Taken together with the potential sequelae of
undiagnosed ABU, it is recommended that urine cultures should be used for all pregnant patients
to detect ABU.