Heliobacter Pylori Testing

As previously discussed in our Fall 2012 issue, Helicobacter pylori (H. pylori)  is a bacteria found in the stomach that can cause a variety of intestinal disorders such as peptic ulcers and gastritis. This bacterium is also a very common cause for dyspepsia, a syndrome consisting of epigastric discomfort, feelings of early fullness after eating, and bloating.

For patients who do not have “alarm” symptoms such as weight loss or vomiting which require a more thorough evaluation, non-invasive testing for H. pylori can easily and effectively diagnose the presence of this bacterium. One such test that is commonly available now is a urea breath test. This test can be used to both diagnose Helicobacter pylori and confirm its eradication. The test requires a patient to provide a sample of their breath about 20 minutes after ingesting a compound. This is based on the fact that H. pylori can covert a compound called urea to both carbon dioxide and ammonia.

During this test, a patient will ingest a detectable type of carbon called an isotope. If H. pylori is present, this isotope will incorporate into carbon dioxide and will then be detectable in the patient’s breath. There are two commercially available tests, and the only difference between these tests is the use of a radioactive isotope in one of the tests. It should be noted that the amount of radiation used in the test is essentially equal to the normal radiation a person is exposed in their daily life.

The urea breath test has a reported sensitivity and specificity of 95%, meaning the chance of a false positive test is very low. False negative tests can also occur, especially if a patient is being prescribed certain medications. The two classes of medications that can cause false negative results include antibiotics and proton pump inhibitors (PPIs) such as Nexium or Prilosec. These medications will suppress but not completely eliminate the presence of H. pylori in the stomach. In order to eliminate this risk, a patient must not use antibiotics for four weeks and PPIs for two weeks prior to undergoing the test.

Another option in terms of non-invasive evaluation is the use of an H. pylori stool antigen test. The antigen is essentially a marker for the presence of active bacteria. This test offers a similar accuracy as compared to urea breath testing in detecting the bacteria. However, it has a slightly higher chance of a false positive result in comparison to the urea breath test, and a similar chance of a false negative result. The main advantage of stool antigen testing is that it is slightly less costly as compared to the breath test.

The urea breath test is an increasingly common way for physicians to safely and accurately diagnose the presence of H. pylori in the most cost effective way possible. The increasing use of this test will undoubtedly lead to this bacterium to be more easily identified and thereby allow more and more patients to reap the benefits of treatment.

IBD and Colon Cancer

Inflammatory Bowel Disease (IBD) is a condition characterized by chronic inflammation of the intestines. The two most common types of IBD are Crohn’s Disease (CD) and Ulcerative Colitis (UC).  Although the overall risk of colon cancer in IBD is only 95 cases per 100,000 – this is much higher than for the general population.

In IBD, the main risk factors for colon cancer are the amount of intestine involved as well as the duration of the disease. It’s been estimated that patients with extensive UC have about a 2.5% increased risk of colon cancer. This increased risk is seen after eight to ten years of disease. This can increase up to 20% after thirty years of disease. Ulcerative Colitis, limited to the left side of the colon, also carries a high risk of colon cancer even though this higher risk is not seen until after 15 years of disease. Crohn’s Disease also carries a higher risk CRC after seven years of disease. Both Crohn’s Disease and UC patients should be screened for colon cancer with colonoscopy every one to two years starting seven years after disease duration.

Cancer in IBD is typically seen in areas of chronic inflammation, which can lead to an abnormal cell growth of colon cells called dysplasia. Dysplasia is known to be a precursor to colon cancer. Detecting dysplasia by colonoscopy has been shown to be an effective manner for preventing deaths in IBD. Dysplasia can be found in both colonic growths as well as a normal appearing colon. This means that frequent biopsies need to be taken throughout the colon in order to try to detect dysplasia. Furthermore, a confirmed finding of dysplasia should lead to a total removal of the colon as there is no way to determine if there is cancer away from an area of dysplasia.

The goal of colonoscopy in IBD is to detect dysplasia. An endoscopist must take multiple biopsies during the procedure in order to get an adequate sampling of the colonic mucosa. It takes up to 33 biopsies to detect dysplasia with a 90% confidence. Besides multiple random biopsies, there are other techniques that can help detect dysplasia including the use of jumbo forceps in order to obtain large biopsies for pathology analysis. Another aid that can be used to better detect dysplasia is chromoendoscopy. This refers to the topical application of temporary stains to better characterize inflammatory changes within the colon. The most commonly used stain, indigo carmine, has been shown to be more effective that a random biopsy protocol in detecting dysplasia.

In conclusion, the presence of IBD carries a high risk for the development of colon cancer. Frequent screening colonoscopy with multiple biopsies is an effective way to prevent the development of colon cancer, and should be standard of care for any patient with IBD.