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

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.

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.

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.

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