According to the American Cancer Society, the number of new cases of colon cancer has risen from 100,000 to 103,170 in 2012. The same is also true for new cases of rectal cancer which rose from 40,000 to 40,290. These numbers indicate that there is a need to detect and monitor occult blood in order for prevention and early detection of gastrointestinal disease. The American Cancer Society recommends that, along with your regular colorectal screenings, fecal occult blood tests are important, as well. When using an FOBT, there are several factors that can skew your test results.

Factors that can interfere with test results:

• Red meats or rare-cooked meat
• Bleeding due to constipation, hemorrhoids or menstruation
• Rectal ointments or medications: Avoid using such medications prior to and during testing.
• Toilet bowl cleansers and deodorizers (if using an at-home fecal occult test)
• Vitamin C levels with greater than 250 mg per day may inhibit the color reaction even though blood is present, resulting in a negative test.
• The mineral oil in laxatives can inhibit the color reaction in the testing card.

Patient Preparation:

Eating a well-balanced diet rich in fiber starting 2 days before the test and continuing on through the test period is highly recommended to ensure accurate results. This diet may include, but is not limited to:

• Meats: Only small amounts of well-cooked chicken, turkey and tuna.
• Vegetables: Generous amounts of both raw and cooked vegetables including lettuce, corn, spinach, carrots and celery (see vegetable exclusions below)
• Fruits: Plenty of fruits, especially prunes and apples (see fruit exclusions below).
• Cereals: Bran and bran-containing cereals.
• Moderate amounts of peanuts and popcorn daily.

Foods to Avoid:

• Meats: Diet should not include any red or rare meat.
• Raw fruits and vegetables that produce high peroxidase activity (as they can produce false positive color reactions in the guaiac slide) such as: turnips, cauliflower, broccoli, red radishes, horseradishes, cantaloupe and parsnips.

Medications that may affect FOBT test results:

• Aspirin
• Indomethacin
• Corticosteroids
• Phenylbutazone
• Reserpine
• Other gastrointestinal irritants
• Dietary iron supplements
• Antiseptic preparations containing iodine
• Anticoagulants
• Antimetabolites
• Cancer chemotherapeutic drugs

Types of Fecal Occult Blood Tests:

• Laboratory Test:  Great for large facilities and hospitals, these are bulk-packaged testing kits designed for large volumes of stool specimens from multiple patients. Laboratory kits generally include single or triple slides, a checking monitor, developer solution, and specimen applicator sticks.
• Physician FOBT:  In-office packs are designed for doctors for in-office testing or testing kits with mail-in envelopes that the patient can return their sample by mail. This testing kit generally includes triple testing slides, developer solution, specimen applicators, mailing envelopes, and patient instruction sheets.
• Home FOBT Kits:  This type of test is designed for individuals to quickly and easily check for blood in the stool in the privacy of their home. Home fecal testing kits are usually less accurate that those administered by a physician, so it is a good idea to speak with your doctor if you have any concerns about traces of blood in your stool, and checking your results professionally to ensure the accuracy of your at-home FOBT.