Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1366 page)

   
Positive result:
Indicates that
H
.
pylori
IgG antibodies were detected in the sample. The presence of IgG antibodies to
H
.
pylori
is an indication of previous exposure to the organism.

   
Negative result:
Indicates that
H
.
pylori
IgG antibodies were not detected in the sample. Negative results by this test do not preclude recent primary infection.

   Limitations

   The ACG guidelines recommend that testing for
H
.
pylori
should be performed only if the clinician plans to offer treatment for positive results.

   Testing is indicated in patients with active peptic ulcer disease, a past history of documented peptic ulcer, or gastric MALT lymphoma.

   The test-and-treat strategy for
H
.
pylori
(i.e., test and treat if positive) is a proven management strategy for patients with uninvestigated dyspepsia who are younger than 55 years of age and have no “alarm features” (bleeding, anemia, early satiety, unexplained weight loss, progressive dysphagia, odynophagia, recurrent vomiting, family history of GI cancer, previous esophagogastric malignancy).

   Deciding which test to use in which situation relies heavily on whether a patient requires evaluation with upper endoscopy and an understanding of the strengths, weaknesses, and costs of the individual test.

   General population screening of asymptomatic patients not recommended.

   Patients with family history of GI cancer should have screening if symptomatic (endoscopy with biopsy).

   Patients without “alarm” symptoms, a dyspepsia that does not respond to antireflux treatment, may be candidates for
H
.
pylori
testing.

HELICOBACTER PYLORI
STOOL ANTIGEN DETECTION

   Definition

   
H
.
pylori
is a bacterium that is found in the stomach of about two thirds of the people in the world, although most infected people will never develop disease.
H
.
pylori
infection is a major risk factor for peptic ulcer disease. These bacteria are responsible for the large majority of gastric ulcers and upper duodenal ulcers. Research studies indicate that infection with
H
.
pylori
increases the risk of gastric cancer, gastric mucosa-associated lymphoid tissue (MALT) lymphoma, and possibly pancreatic cancer.
H
.
pylori
infection may be diagnosed by invasive (e.g., histopathology) or noninvasive (e.g., serology, breath urea test, stool antigen) tests. Most tests use an EIA format. Tests using monoclonal antibodies against
H
.
pylori
have reported the best accuracy.