Diagnosis of Helicobacter Pylori Infection
A medical history and physical examination are beginning steps in diagnosing H. pylori infection. Information about any family history of stomach cancer or related illnesses and about the frequency and severity of symptoms is important.
During physical examination, the physician feels the abdomen to detect an obvious mass. Results of the medical history and physical exam, as well as the age and overall health of the patient, help to determine whether noninvasive or invasive diagnostic tests are performed to confirm the diagnosis.
Laboratory tests include blood tests, stool antigen tests, and breath tests. A blood test, often involving a finger stick, is the most common test for Helicobacter pylori infection. This test is used to detect antibodies to H. pylori bacteria in the blood.
Stool antigen tests may be performed to detect proteins called antigens in the stool. The presence of antigens indicates infection in the GI tract.
Breath tests can be more accurate than blood tests to diagnose H. pylori infection, but they must be conducted in a hospital. In this test, the patient drinks a solution that includes radioactive carbon atoms along with a chemical called urea. If H. pylori bacteria are present in the digestive tract, they break down the urea and release carbon, which is then carried to the lungs through the blood. When the patient exhales, a medical device is used to detect the carbon. This test usually takes about a half hour to administer and has a 96–98 percent accuracy rate.
Imaging Tests to Diagnose Helicobacter Pylori Infection
Patients who have severe symptoms, are over the age of 55, or have a family history of stomach cancer may require more invasive tests to diagnose H. pylori infection.
Because it allows for tissue samples (biopsy), a procedure called endoscopy is usually the preferred imaging test for diagnosing H. pylori infection. This test allows the physician to examine the digestive tract directly using a long tube with a camera attached at the end (called an endoscope). In this test, the endoscope is passed through the throat and into the esophagus, stomach, and intestines.
During endoscopy, tissue samples can be removed for microscopic analysis using instruments passed through the endoscope. Common tissue tests include the following:
- Rapid urease test (used to detect and an enzyme called urease, which indicates the presence of H. pylori bacteria)
- Histology test (used to detect H. pylori bacteria themselves)
- Culture test (used to grow bacteria in the tissue sample for further study)
X-rays also may be used to examine the abdomen. In a barium upper gastrointestinal (GI) series, also called an upper GI, the patient drinks an oral contrast solution (barium) that coats the stomach lining, making it easier to locate damage or infection. Another x-ray procedure involves ingesting a substance that produces gas and causes the stomach to stretch, flattening the lining. Air contrast can help the physician examine the stomach lining more closely.