BACKGROUND: Helicobacter pylori has been linked to chronic gastritis, peptic 
ulcers, gastric cancer and mucosa-associated lymphoid tissue lymphoma. Invasive 
tests are less sensitive than noninvasive tests in diagnosing H. pylori 
infection in patients with bleeding peptic ulcers. The H. pylori stool antigen 
test has been useful in diagnosing H. pylori in patients with peptic ulcers 
before and after eradication of H. pylori. The aim of this study was to evaluate 
the H. pylori stool antigen test in patients with bleeding peptic ulcers.
METHODS: Patients with bleeding and nonbleeding peptic ulcers underwent a rapid 
urease test, histology, bacterial culture and H. pylori stool antigen test. 
Positive H. pylori infection was defined as a positive culture or both a 
positive histology and a positive rapid urease test. Helicobacter pylori stool 
antigen was assessed with a commercial kit (Diagnostec H. pylori antigen EIA 
Kit, Hong Kong).
RESULTS: Between October 2000 and April 2002, 93 patients with bleeding peptic 
ulcers (men/women: 78/15, gastric ulcer/duodenal ulcer: 58/35) and 59 patients 
with nonbleeding peptic ulcers (men/women: 47/12, gastric ulcer/duodenal ulcer: 
30/29) were enrolled in this study. Forty-seven (50.5%) patients with bleeding 
peptic ulcers and 30 (50.8%) patients with nonbleeding peptic ulcers, were found 
to be infected with H. pylori (p > .1). Helicobacter pylori stool antigen tests 
were positive in 54 (58.1%) and 30 (50.8%) patients with bleeding peptic ulcers 
and nonbleeding peptic ulcers, respectively (p > .1). The sensitivity (82% vs. 
93%), specificity (68% vs. 93%), positive predictive value (74% vs. 93%), 
negative predictive value (77% vs. 93%) and diagnostic accuracy (75% vs. 93%) 
were all lower in patients with bleeding vs. nonbleeding peptic ulcers. The 
specificity, positive predictive value, and diagnostic accuracy of the H. pylori 
stool antigen test in patients with bleeding peptic ulcers were significantly 
lower than those in patients with nonbleeding peptic ulcers (p = .01, p = .02 
and p = .003, respectively).
CONCLUSION: The H. pylori stool antigen test is not reliable for diagnosing H. 
pylori infection in patients with bleeding peptic ulcers.