Rapid urease test: effect of preimmersion of biopsy forceps in formalin.

Objective: The rapid urease test is widely used at endoscopy to determine the presence of Helicobacter pylori. The effect of immersion of the biopsy forceps in formalin before performance of a rapid urease test is uncertain. The aim of this prospective study was to determine whether previous immersion of the biopsy forceps in formalin influences rapid urease test results.

Methods: Two hundred fifty-three consecutive patients undergoing upper GI endoscopy with a clinical indication for rapid urease test had two tests with two different antral mucosa biopsies. The former was performed with a sterile biopsy forceps, the latter with a sterile biopsy forceps that was previously immersed in 10% buffered formalin. In 132 patients the CLOtest was used and in 121 patients the Jatrox-H.P. test was used. The kappa concordance test was used for comparisons.

Results: In the 132 patients in which the CLOtest was used, both were positive in 76 cases, both negative in 27, and discordant results were seen in 3 cases (2.27%), kappa 0.953 (range 0.901-1.000, p < 0.001). In the 121 patients in which the Jatrox test was used, both were positive in 89, both negative in 27 and there were 5 (4.13%) discordant cases, kappa 0.880 (0.793-0.984, p < 0.001). There were no differences in positivity rates at 30 minutes, 1 hour, and 3 hours between the two rapid urease test kits.

Conclusion: Preimmersion of the biopsy forceps in formalin does not adversely affect the rapid urease test.