EFFECT OF BLOOD ON RAPID UREASE TESTING OF GASTRIC-MUCOSAL BIOPSY SPECIMENS

Background: The effect of blood on rapid urease tests is uncertain. We assessed the effect of soaking gastric biopsy specimens in blood on t he results of both agar gel (CLOtest) and strip (Pyloritek) rapid urea se tests. Methods: One hundred patients undergoing endoscopy had four adjacent biopsy specimens taken from normal appearing mucosa in the an trum. Two biopsies were soaked in blood for 1 minute; one specimen was placed on a CLOtest and one on a Pyloritek. The other two biopsy spec imens were placed on CLOtest and Pyloritek without soaking in blood. T he same process was performed with four adjacent biopsy specimens from the gastric body. CLOtests were read at 1, 4, and 24 hours; Pyloritek results were read at 1 hour. Results: The number of positive tests fo r the blood-soaked and standard biopsy specimens were comparable at al l times for both rapid urease tests. Discordant results between the bl ood-soaked and standard specimens were seen in 17 of 400 test comparis ons (4%): in 8 of these only the blood-soaked specimen was positive, a nd in 9 only the standard specimen was positive. Conclusions: ''Contam ination'' of biopsy specimens with blood does not alter rapid urease t est results.