| ENCYCLOPEDIA INDEX |
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Injury Disease Nutrition Poison Symptoms Surgery Test |
| 1 2 5 A B C D E F G H I J K L M N O P Q R S T U V W X |
Fecal occult blood test (FOBT) |
| Overview Risks Results |
| Alternative Names: |
| Stool occult blood test |
| What the risks are: |
| A negative test does not necessarily mean there are no colorectal diseases present. Not all polyps bleed, and not all polyps bleed all the time. That is why a FOBT must be used with one of the other more invasive screening measures (sigmoidoscopy, colonoscopy, double barium contrast enema). |
| Special considerations: |
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Colonoscopy is generally recommended as the preferred follow-up test to a positive FOBT. Factors that can cause this test to be less accurate include the following:
Drugs that can cause GI bleeding include anticoagulants, aspirin, colchicine, iron supplements in large doses, NSAIDs (anti-inflammatory analgesics), and corticosteroids. Drugs that can cause false positive measurements include colchicine, iron, oxidizing drugs (for example, iodine, bromides, and boric acid), and reserpine. Large amounts of vitamin C can cause false-negative results on most FOBTs. |
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