The effects of blood on rapid urease testing for Helicobacter pylori in mucosal biopsies from the gastric antrum

Background While the eradication of Helicobacter pylori in patients with bl eeding peptic ulcer disease (PUD) decreases the rate of ulcer re-bleeding, the sensitivity of the rapid urease test (RUT) for H. pylori diagnosis is l ower in this setting, The aim of this study was therefore to determine if e xposing a gastric biopsy specimen to blood before its use in the RUT (CLOte st) could account for these findings. Methods In patients undergoing endoscopy for the evaluation of dyspepsia ga stric mucosal biopsies were obtained for H, pylori diagnosis (RUT, microbio logy, and histology), Mucosal biopsies from each patient were also exposed to blood for 15, 30 and 45 minutes before use in the RUT. Results Using a combination of diagnostic tests (histology, microbiology an d routine CLOtest) as the 'gold standard', the sensitivity, specificity, po sitive predictive value and negative predictive value of the CLOtest remain ed above 90% despite prior exposure of the gastric biopsy specimen to blood , and these values were not significantly different from the performance ch aracteristics of the CLOtest processed in a routine manner. Conclusion The exposure of gastric mucosal biopsy specimens to blood alone is not the explanation for the reduced sensitivity of the RUT in patients w ith bleeding peptic ulcers.