Use and purpose
The hemoccult test is a home test that’s used to detect the presence of occult blood in your stool. Occult blood is blood in your stool that you can’t see in the toilet or on the toilet paper after you have a bowel movement.
The hemoccult test is predominantly used as a diagnostic tool for colorectal cancer. The idea behind it is that large polyps present in your colon are fragile and can be damaged by the movement of stool. This damage causes the polyps to bleed into the intestine. The blood is then passed with the stool, but it’s often not enough to be detected with the naked eye. Noticeably bloody stools may be a sign of other conditions.
The American Cancer Society recommends that hemoccult be tested every year after you turn 50. If you’re at an increased risk for colorectal cancer or have a family history of colorectal cancer, your doctor may want you to be tested every year after you turn 40. As you age, certain tests should be done regularly so you can maintain your best possible health.
How it’s done
The hemoccult test comes in a kit that you can use at home. You’ll receive instructions from your doctor regarding sample collection. It’s important to make sure that you have the specific collection instructions provided to you by your doctor.
Before collecting the sample, make sure you have everything that you’ll need nearby. A typical hemoccult test contains the following:
- test kit
- test cards
- wooden brush or applicator
- mailing envelope
If there’s a place on the test cards to enter your name and the dates of collection, fill that out before collecting the sample.
Guidelines for hemoccult test sample collection are as follows:
- You’ll need to collect samples from three separate bowel movements, spaced as closely together as possible. Typically, this will be on three consecutive days.
- The stool sample should be collected in a clean container and not be contaminated with urine or water.
- Use the provided applicator stick to smear a thin sample of stool onto the designated area on the test card and allow to dry. The samples should be stable for several weeks at room temperature once they’ve dried.
- Once you’ve collected all three samples, use the mailing envelope to send the samples to the laboratory for testing.
It’s recommended that you do the following in the days leading up to your hemoccult test:
- If you’re eating vegetables or fruit, make sure that they are cooked well.
- Eat a high-fiber diet that includes cereals and breads with bran.
- Avoid nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin (Bufferin) or ibuprofen (Advil, Motrin), for seven days prior to testing. NSAIDs can cause bleeding in the digestive tract, which could lead to a false positive result.
- Avoid vitamin C consumption greater than 250 milligrams per day. This includes vitamin C from both dietary supplements and fruit. Otherwise, you might get a false negative result. If possible, you should avoid vitamin C for three days prior to testing.
- Avoid red meats, such as beef and pork, for three days prior to testing. Blood from the meat could lead to a false positive result.
- Avoid raw turnips, radishes, broccoli, and horseradish. Eating these can also lead to a false positive result.
What the results mean
The hemoccult blood test uses a chemical reaction to detect occult blood in your stool. The results for the hemoccult test are either positive or negative:
- A positive result means that occult blood has been detected in your stool. It doesn’t mean that you have colorectal cancer. If the results of your hemoccult test come back positive, then you’ll need to have a colonoscopy to determine the source of the blood. If you do need a colonoscopy, here are some helpful tips for how to prepare.
- A negative result means that no blood has been detected in your stool. If you have no additional risks for developing colorectal cancer other than age, your doctor will recommend that you be tested again the following year.
Limitations of the test
The hemoccult test is qualitative and not quantitative. That means that it only detects whether or not there is occult blood present in your stool, not the actual amount. If you have a positive result, you’ll need further testing, such as a colonoscopy.
The hemoccult test is also not always accurate. If you have polyps that don’t bleed, the hemoccult test will return a negative result. Also, the hemoccult test can’t detect whether the blood is coming from your colon or another part of your digestive tract. If you have bleeding elsewhere in your gastrointestinal tract, such as in the case of an ulcer, the test will come back positive.
Lastly, the hemoccult test can’t detect all cancers. Some cancers can be detected through the use of colonoscopy but not through the hemoccult test.
The hemoccult test is used as a tool in the diagnosis of colorectal cancer. The test is performed in the privacy of your home with materials supplied by your doctor or clinic. The test detects the presence of blood in your stool, which can be a sign that you have polyps present in your colon.
The results are either positive or negative, though false positives and false negatives are possible. If you receive a positive result, you’ll need to have a colonoscopy to confirm the results and the source of the blood.
The hemoccult test isn’t always accurate and can’t detect all cancers, but it’s a helpful tool. It’s important to follow all of your doctor’s instructions when doing this test.