Hemoccult Card Test

Hemoccult card test kit and instructions

Colon Polyp on Stalk
Ready to Snare Polyp
Snare Wire Over Polyp
Residual Cauterized Stump

Hemoccult Card Test
(for hidden blood in the stool)
Tina: How a visit to her gynecologist saved her life.... Tina F. is a 52 year old school psychologist who sees her gynecologist every year for a routine checkup. Like many women, she does not have a family doctor, but uses her gynecologist as her personal physician. This year her doctor suggested that a routine stool Hemoccult test be performed in addition to her annual blood tests and physical exam. As she left the office, the nurse gave her a Hemoccult card test kit and instructions. Tina collected the stool specimens as instructed and mailed the card back to her doctor's office for testing. She was surprised to receive a letter from her doctor the next week informing her that the Hemoccult test found traces of hidden blood in her stool. Tina was especially surprised since she never had any problems with bowel movements and never noticed any blood in her stool. She was referred to our office and a colonoscopy exam was performed to determine the cause of the bleeding.

The colonscopy exam went well and found the cause of Tina's bleeding - an inflamed colon polyp that was located in her right colon. It was slowly oozing small amounts of blood and was the source of the trace of hidden blood in the stool. In this series of photos, you can see how the polyp was removed during colonoscopy using a thin wire electrocautery snare. It was a simple outpatient procedure and she was back to work the next morning.

Tina was pleased that her problem could be cured with a simple painless outpatient procedure and she was back to work the next morning. The polyp was sent for a biopsy. We called Tina the next week and informed her that she was very lucky. The biopsy showed that her polyp was "highly dysplastic with carcinoma-in-situ bordering on adenocarcinoma" - about as close as you can get to cancer, without actually being malignant. Her gynecologist did her a great service by being thorough and discovering her rectal bleeding even before it was visually apparent. The discovery and removal of this type of colon polyp saved Tina from having to deal with colon cancer in her future and probably saved her life. She will be scheduled to return for a follow-up colon exam periodically in the future.

What is a Hemoccult test?

The Hemoccult test, a product of SmithKline Diagnostics, Inc., is a simple screening test which detects blood in the stool (bowel movements). It is a very sensitive test and can detect a small trace of blood even before it is visible to the naked eye. In medicine, the prefix "heme" refers to blood, as in "hematology". Blood which is hidden from view is called "occult" bleeding (nothing to do with witchcraft), hence the name Hemoccult for "hidden blood". Other tests for occult blood are also on the market (Colocare, EZ Detect), but the most commonly used test is the Hemoccult.

Why do this test?

Prevention - the purpose of the stool Hemoccult test is to help prevent colon cancer by searching for hidden (occult) blood in the stool before it has become so apparent to be visible. The American Cancer Society estimates that over 130,000 people developed colorectal cancer in 2000. Not only is this a common disease, it is quite sneaky. In fact, the majority of patients with colon cancer are incurable when they have their first symptom. Despite undergoing the rigors of heroic treatment such as surgery, radiation, and chemotherpay, most paients succumb to their disease. In advanced stages, the overall cure rate is quite low. Over 56,000 Americans died last year from colon cancer.

However, when colorectal cancer is detected in an early localized stage, up to 85% of colorectal cancers can be treated successfully. When cancer is detected after symptoms appear and it has spread to other parts of the body, fewer than 7% may be treated successfully. This means that earlier detection could save thousands of lives each year. In some cases, the Hemoccult test will show hidden blood in the stool in early curable stages of colon cancer. Even better, as in this case, the Hemoccult test may be positive even before cancer cells have developed.

How is it done?

It is quite simple. To complete the test, you place a thin smear of a small stool specimen, taken from your toilet bowl, onto the window inside the test slides included in your kit. You do this twice from each of three consecutive bowel movements and mail the completed card back to your doctor's office in the special envelope. To maximize the accuracy, some special precautions are suggested:

  • Do not collect samples during, or until three days after your menstrual period, or while you have bleeding hemorrhoids or blood in your urine.
  • Remove any cleaning or deodorizing agents from the toilet and flush twice.
  • For 3 days before the test, avoid Vitamin C tablets, iron tablets, red meat (rare, cooked and processed beef, lamb and liver), raw broccoli, cauliflower, horseradish, parsnips, radishes, turnips and melons.
  • Protect slides from heat, light and chemicals. Keep cover flap of slides closed when not in use.

What happens after the Hemoccult card is returned?

After the stool collection is complete, the Hemoccult card is mailed back to the doctor's office or lab in a special protective envelope for testing. Testing the card is quite quick and simple. The medical technician opens the flaps on the back of the card and applies a few drops of a special chemical developing solution onto each of the three stool specimens. If hemoglobin (a special blood protein found in red blood cells) is present in the stool, it reacts with the developing solution turning blue. This is an abnormal result and means that traces of blood are present. To be sure the the card and developing solution are fresh and active, a quality control strip is included on the back of each card. Normally, the developing solution turns this control strip blue which means the card can be trusted.

Positive Test

The developer turns the stool specimen blue - this is an abnormal result and means that blood is present in that stool specimen.

Negative Test

If the stool specimen does not turn blue, then no hidden blood is present. This is a normal result.

Who should do a Hemoccult test?

All adults over 40 should do this test annually even if there are no symptoms. This really should just be part of an annual checkup from your family doctor or gynecologist.

Who should NOT do a Hemoccult test?

Anyone with visible rectal bleeding. This test looks for hidden blood in the stool - before it is visible to the naked eye. If an individual has visible blood in the stool, there is no reason to do a Hemoccult test. You already know that bleeding is present and needs to be evaluated.

What if it is abnormal (POSITIVE)?

Don't panic! A positive Hemoccult test (one that shows blood) does not diagnosis cancer. It simply means that there is blood in the stool that is not supposed to be there. There are many possible causes for blood in the stool which have nothing to do with colon cancer such as hemorrhoids, fissures, ulcers, and, as in the above example, colon polyps. The important point is that when a Hemoccult test is positive for occult blood, you must see your doctor for further testing to determine the cause. The safest approach is to assume that the cause is colon cancer until proven otherwise. Most adults who have an abnormal stool Hemoccult test will be referred to a gastroenterologist for further evaluation. As in Tina's case, this will usually include an examination of the colon, or colonoscopy. If the colon test is normal, the doctor will sometimes suggest that the upper digestive tract be evaluated in a similar fashion by also performing a gastroscopy test. Usually, both "scope" exams can be done on the same visit.

What if it is normal (NEGATIVE)?

That sounds reassuring, but perhaps falsely so. The Hemoccult test is a test for blood, not cancer. The surface of a colon cancer is delicate and may bleed easily. In fact, this is the very basis of the test itself. But, you should know that most colon cancers and polyps bleed intermittently. They may lose a small amount of blood one day and not bleed again for several days. Some don't bleed at all - especially in early curable stages. So, a normal (NEGATIVE) stool Hemoccult test misses about 60% of colon polyps and 40% of colon cancers. Not very reassuring. This is really a screening test that has some significance only if abnormal (POSITIVE). The Hemoccult test is meant to be just a part of colon cancer prevention, but must be supplemented with more ac curate examinations of the colon, such as a screening sigmoidoscopy, a screening colonoscopy, or a barium enema.

How accurate is the Hemoccult test?

Not very. As mentioned above, the Hemoccult test is very sensitive for finding occult blood in the stool when present. It does so about 98% of the time. But since colon cancer and polyps may not bleed during the time of stool collection, a normal result may miss colon cancer and polyps up to 60% of the time. However, doing a Hemoccut test is better than doing nothing at all - which is what most adults do. The Hemoccult will still pick up about 40% of cases that would have been missed if no testing was done. However, the Hemoccult test should not be relied upon as the sole screening method.


The Hemoccult test is a simple, inexpensive, non-invasive stool test that can be collected in the privacy of your home. It is not a test for colon cancer, but detects hidden (occult) blood in the stool before it becomes visible. A normal test should not be reassuring since it misses over half of the colon cancers and polyps. It is not meant to be used alone, but must be part of a comprehensive colon cancer screening program which include other screening exams. A positive test should not cause panic, but must be further investigated to determine the source of bleeding. Only diagnostic testing from a physician can determine the cause of the bleeding. Used correctly, the stool Hemoccult test can be an important aid in detecting cancer in its early stages of development. If you have further questions, discuss them with your doctor.

Text & Images Courtesy of Three Rivers Endoscopy Center
© Dr. Robert Fusco, Three Rivers Endoscopy Center, All Rights Reserved

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