Evaluation of rapid urine screening tests to detect asymptomatic bacteriuria in pregnancy

In order to compare the performance of leukocyte esterase and nitrite urine dipstick tests with enhanced urinalysis (uncentrifuged urine white blood cell count/mm(3) plus Gram stain) in detecting asymptomatic bacteriuria in obstetric patients, clean-catch midstream urine specimens were collected from 250 consecutive asymptomatic pregnant women. Ten of the women (4.0%) showed urine culture results indicating significant bacteriuria. The nitrite test was the most specific (99.2%) of these tests, however, its sensitivity was found to be the lowest (60.0%). The sensitivity of the leukocyte esterase test was 70.0%, on the other hand, while its positive predictive value was 28.0%. The sensitivity and specificity of enhanced urinalysis were found to be 50.0 and 96.7%, respectively. None of the rapid tests was found to be a reliable alternative for culture screening of all pregnant women. Nitrite tests are useful screening tests for detecting asymptomatic bacteriuria only if their limitations are fully understood, while leukocyte esterase and enhanced urinalysis tests are not suitable for screening for asymptomatic bacteriuria. Our findings support previous conclusions that quantitative urine cultures are required to rule out asymptomatic bacteriuria in pregnant women.