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 bleeding peptic ulcer disease (PUD) decreases the rate of ulcer re-bleeding, the sensitivity of the rapid urease test (RUT) for H. pylori diagnosis is lower in this setting. The aim of this study was therefore to determine if exposing a gastric biopsy specimen to blood before its use in the RUT (CLOtest) could account for these findings.


METHODS
In patients undergoing endoscopy for the evaluation of dyspepsia gastric mucosal biopsies were obtained for H. pylori diagnosis (RUT, microbiology, 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 and routine CLOtest) as the 'gold standard', the sensitivity, specificity, positive predictive value and negative predictive value of the CLOtest remained above 90% despite prior exposure of the gastric biopsy specimen to blood, and these values were not significantly different from the performance characteristics of the CLOtest processed in a routine manner.


CONCLUSIONS
The exposure of gastric mucosal biopsy specimens to blood alone is not the explanation for the reduced sensitivity of the RUT in patients with bleeding peptic ulcers.
Lee
J M
JM
Department of Gastroenterology, Meath Hospital, Trinity College, Dublin.
Breslin
N P
NP
Gopaul
M
M
Koh
C W
CW
Kong
T Y
TY
Soong
M M
MM
O'Morain
C A
CA
D000328:Adult; D000368:Aged; D001769:Blood; D005753:Gastric Mucosa / Q000382:microbiology*; D016481:Helicobacter Infections / Q000097:blood / Q000175:diagnosis*; D016480:Helicobacter pylori / Q000302:isolation & purification*; D006801:Humans; D008875:Middle Aged; D010438:Peptic Ulcer Hemorrhage / Q000097:blood / Q000175:diagnosis / Q000382:microbiology*; D011237:Predictive Value of Tests; D011706:Pyloric Antrum / Q000382:microbiology; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D014510:Urease
D011933:Reagent Kits, Diagnostic; D014510:Urease