Physicians frequently order fecal tests for occult blood for their patients. The test can help determine if the patient has colorectal cancer or bleeding throughout their gastrointestinal tract. It is called an occult blood test because it can find blood unseen by the human eye. A positive result means blood may be present in the stool. Many foods can interfere with the test results. The following is a list of the foods that should be avoided for three days prior to, and during the administration of the test.
Foods That Contain Blood
Foods that contain blood must be avoided. These include red meat (such as beef steaks, hamburger meat, pork chops, sausage, veal and lamb), poultry and fish. Wild game and exotic meats should also be avoided.
Foods That Give False Positive Results
Some vegetables and fruits contain a chemical that can give a false positive result on a stool occult blood test. They include turnips, cabbage, cucumbers, broccoli, carrots, cauliflower, horseradish, beets, radishes, mushrooms and cantaloupes and other melons. Avoid eating raw vegetables and do not consume hot sauce.
Foods That Give False Negative Results
Some foods contain a chemical that gives a false negative result on a fecal occult blood test. These foods include grapefruits, oranges, tangerines and tangelos. You should also avoid drinks and foods that contain added vitamin C.
Other Considerations
You should avoid taking blood thinners including aspirin for three days before and during the test. Discuss with your doctor what medications you should withhold during this period and do not stop taking any medication without her approval. Avoid taking vitamin C or a multivitamin containing it. Do not take the test while you are menstruating. If you have hemorrhoids make sure they are not bleeding when you are tested. A sore throat can also cause minute bleeding and lead to a positive result. Do not have dental work performed or aggressively brush your teeth until your gums bleed. Do not use any toilet bowl cleaner for several days prior to the test and make sure you do not have a long-term cleaner in the tank.
Fecal occult blood tests are generally ordered annually for people age 50 and over and as needed for younger people. The test should not stand alone as a determinant for colorectal cancer and other diagnostic tests should still be performed on a patient who tests negative.
If Your Test Is Positive
If your test is positive, the physician may order the test repeated or begin searching for the source of the bleeding. A colonoscopy or other diagnostic test may be performed to rule out colorectal cancer. There are many reasons for occult blood in the gastrointestinal tract, many of which are not life threatening.
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