The Griess test: an inexpensive screening test for asymptomatic bacteriuria in pregnancy.

This study was designed to compare urine microscopy and the Griess test as screening tests for asymptomatic bacteriuria (AB) in pregnancy, using urine culture as a gold standard. Urine microscopy, Griess test and urine culture were carried out on urine samples from 483 antenatal women. AB was detected by urine culture in 30 (6.8%) of the patients. The Griess test and urine microscopy were found to have a sensitivity of 63.3% and 60%, specificity of 99.5% and 83.6%; and positive predictive value of 90.5% and 21.1% respectively. Most of the infections missed by the Griess test were either <100,000 colony count on culture or caused by gram positive cocci. The cost of the Griess test was only one tenth of that of urine microscopy. The Griess test is a simple and inexpensive test that when compared to urine microscopy has equal sensitivity, and better specificity and positive predictive value for the detection of AB in pregnancy than urine microscopy.