test Details

Colorectal cancer

Occult blood is blood that you cannot see with your naked eye. It is the blood in your stools caused by bleeding from your digestive tract. The bleeding may be caused due to polyps, haemorrhoids (piles), diverticulosis, ulcers or colitis (a type of inflammatory bowel disease).

Blood in your stools is a sign of colorectal cancer. Colorectal cancer is a type of cancer of your colon and rectum. Studies show that annual incidence rates of colon cancer and rectal cancer in men are 4.4 per 1,00,000 and in women are 3.9 per 1,00,0000.

The stool occult blood test helps detect blood in your stool sample. It is used for the screening of colorectal cancer. You can also use the stool occult blood test for finding the cause of bleeding in your digestive tract.

The stool occult blood test is prescribed for screening colorectal cancer and other conditions that cause bleeding in the gut.

Other names of the test

• Occult Blood Test
• Faecal Occult Blood Test
• Haemoccult Test
• FOBT

What does the test measure?

The stool occult blood test detects the presence of blood in your stool sample. Bleeding from anywhere in your digestive tract is excreted from your body via your stools. The blood may be in tiny amounts in your stool and hence cannot be seen by the naked eye. The stool occult blood test detects this minute amount of blood in your stools and helps in the screening of colorectal cancer and other conditions that cause bleeding in your digestive tract.

Who is the test prescribed for?

The stool occult blood test is prescribed for all age groups and both genders. This test is prescribed in the following cases:

• If you are above 45 years of age.
• If you have a family history of colorectal cancer.
• If you are a cigarette smoker.
• If you chew tobacco.
• If you are obese.
• If you drink excessive alcohol.

Causes of blood in stools

• Benign (noncancerous) or malignant (cancerous) growth in your colon (polyps in your colon)
• Anal fissures - splits or cracks in the lining of your anal opening
• Intestinal infections that result in inflammation
• Ulcers
• Ulcerative colitis
• Haemorrhoids (piles) - Swollen blood vessels around your anus or near the lower part of your rectum that can rupture and cause bleeding
• Crohn’s disease
• Diverticular disease - A condition where your colon wall forms outpouchings
• Abnormalities of the blood vessels in your large intestine

If the amount of blood in the stool is in minimal quantities, it may not be visible to the eye. It could be due to minor gastrointestinal bleeding.

If the amount of blood in the stool is in larger quantities, the stools may be black-tar-like in colour, known as melena.

Based on the results of the stool occult blood test, the doctor may require some other tests to confirm the clinical diagnosis.

The stool occult blood test results give you a report of the presence or absence of blood in your stools.

Normal stool occult blood test ranges may vary depending on the laboratory.

A positive stool occult blood test result means blood was found in the stool sample. You may need to undergo further tests like a colonoscopy and other blood tests to confirm the cause of bleeding. The colonoscopy will tell whether the bleeding is from the stomach or the small intestine.

A negative stool occult blood test result means no blood was found in the stool sample. You may need to repeat the test after a year if you are at high risk for colorectal cancer.

The stool occult Blood Test requires a sample of your stools. This test is usually combined with other regular tests.

Test Preparation

The stool occult blood test procedure takes a sample of your stools for testing. It does not require any special preparation. However, if you are on any medicines like vitamin C supplements, iron supplements, or non-steroidal anti-inflammatory drugs (NSAIDs) like aspirin, ibuprofen, naproxen or blood thinners, then you may need to stop these medicines before your stool occult blood test.

a. Before the stool occult blood test:

You will have to stop eating red meat, raw vegetables and fruits at least 48-72 hours before the stool occult blood test. You will also have to stop medicines like vitamin C, iron supplements, NSAIDs and blood thinners. You will have to consult your doctor before taking the test.

b. During the stool occult blood test:

It is a simple stool test that will get over in 5-10 minutes.

c. After the stool occult blood test:

There are no restrictions after the stool occult blood test. Therefore, you can resume regular activity after the test.

For the stool occult blood test, you are required to give your stool sample 3 days in a row. In the case of colon cancers, the stool sample is collected every alternate day as the patient may not bleed daily.

Test inclusions: What parameters are included in the test?

The parameters included in the stool occult blood test are the presence or absence of blood in your stools.

How frequently should you take this test?

Your doctor may repeat the stool occult blood test based on your diagnosis and symptoms. If you start your treatment for colorectal cancer or other gut-related issues, the stool occult blood test may be repeated every 3-4 weeks to check if the treatment is working. Regular monitoring and testing allow your doctor to check the prognosis of your disease and how you are responding to the treatment. In addition, follow-up tests of the stool occult blood test help provide detailed information about the severity of the disease and how the disease has progressed over time.

If you have completed your course of treatment, your doctor may repeat the stool occult blood test every year to check for relapse of cancer, along with a stool DNA test every three years and a colonoscopy every ten years.

If you are above 45 years of age, you may need to repeat the stool occult blood test every year.