The Griess Test: An Inexpensive Screening Test for Asymptomatic Bacteriuria in Pregnancy
Authors: Mathews Jiji E. , George Susan , Mathews Prasad , Mathai Elizabeth , Brahmadathan K. N. , Seshadri Lakshmi 
Published: February 2008

EDITORIAL COMMENT: We accepted this paper for publication, even though the test it describes is not new (A), to remind practitioners that this is a method for screening women for asymptomatic bacteriuria in pregnancy without the expense of culturing a mid‐stream specimen of urine. The Griess test will be more familiar to most readers as the detection of urinary nitrates, which is possible using commercially available dipsticks without the necessity for the preparation of the Griess reagent. These dipsticks often also incorporate a test for leucocyte esterase activity. Whilst the individual specificities of the urinary nitrites and leucocyte esterase activity are probably too low to be used as sole screening tests for asymptomatic bacteriuria in pregnancy, the combination of the tests (either test abnormal) has a sensitivity of 92% and a specificity of 95% when compared with formal urine culture (B). The dipstick test is approximately 1/100th the cost of urine culture, so those practitioners who do not perform a urine culture at the booking visit because of cost may wish to consider testing urine for the presence of nitrites and leucocyte esterase activity, and reserving urine culture for those positive for one of the screening tests. Treatment of asymptomatic bacteriuria in pregnancy is associated with a clear and significant decrease in the risk of preterm delivery (C).

Peter Wein, FRACOG, Melbourne

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Summary: 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.