The effect of blood on rapid urease test for Helicobacter pylori detection: an in vitro study.

ABSTRACT

The sensitivity of rapid urease test (RUT) for detecting Helicobacter pylori (H. pylori) is limited in patients presented with bleeding peptic ulcers. Blood contents are potentially responsible for the lack of sensitivity of RUT in patients with upper gastrointestinal bleeding. This study was designed to determine the efficacy of RUT in detecting H. pylori when exposed to the patients' own blood at varying durations. Four gastric antral biopsy specimens were collected from dyspeptic patients who underwent gastroscopic examination. The first specimen was immediately placed into the urea broth as the control group. The second, third and fourth specimens were immersed in the patients' own blood for one, two and four hours respectively before testing for the RUT. The results of these RUT were compared to those of the control group. Gastric antral biopsy specimens tested with the RUT of twenty patients were evaluated in this study. The 1-hour RUT and 2-hour RUT was not significantly different in sensitivity (92.31% vs 100% p>0.05, 84.62% vs 100% p>0.05 respectively) and accuracy (95.0% vs 100% p>0.05, 90.0% vs 100% p>0.05 respectively) compared to the unexposed blood RUT for H. pylori diagnosis. However, the study demonstrated that the 4-hour RUT had significantly lower sensitivity (53.85% vs 100% p<0.05) and accuracy (70.00% vs 100% p<0.05) than that of the unexposed blood RUT for H. pylori diagnosis. It is concluded that exposure of gastric biopsy specimens to their own blood for four hours significantly decreased the sensitivity of the biopsy rapid urease test for H. pylori detection.