Faecal Occult Blood Test: What to Expect

Sometimes, changes to your body can be subtle and easy to miss. Small amounts of blood in your stool, for example, often present no obvious symptoms. Yet they can indicate digestive system problems that require attention. Detecting these changes early can make a difference.

One way doctors can look for hidden blood in the stool is with a faecal occult blood test (FOBT). This non-invasive test can provide peace of mind or an early warning, helping to guide the next steps for your health.

What is a faecal occult blood test?

A faecal occult blood test (FOBT) is a laboratory test that checks for tiny amounts of blood in your stool (bowel motion or poo) that cannot be seen with the naked eye. The word “occult” simply means “hidden”. 

This test helps doctors find signs of bleeding in the digestive system, which may need further investigation. There are two main kinds of FOBT which are the guaiac-based test (gFOBT) and the immunochemical test (iFOBT or FIT).

What is it used for?

A faecal occult blood test (FOBT) is mainly used to check for small, hidden amounts of blood in the stool. The test can help detect early signs of bowel (colon) problems and is used for the following reasons:

• Screening for bowel cancer:

  • The test is commonly used as part of routine bowel cancer screening in people who have no symptoms.

  • Hidden blood in the stool may be an early sign of bowel cancer or precancerous polyps in the colon or rectum.

• Investigating unexplained anaemia:

  • The test may be done to look for hidden bleeding that could explain low iron levels or anaemia.

• Helping to assess bowel disorders:

  • It may assist doctors in distinguishing between different types of bowel conditions.

If blood is found in your stool, further tests will be required to determine the source of the bleeding, such as a colonoscopy. A faecal occult blood test only shows whether blood is present; it does not indicate where the bleeding is coming from. This test is not suitable if you are already experiencing symptoms such as blood in your stool, abdominal pain, or a change in your usual bowel habits.

If you are at a higher risk of bowel cancer, for example if you have previously had colon polyps or if you have a close family member with the disease, it's recommended that you speak with a doctor. Schedule an appointment with Thomson Medical today.

Why do I need a faecal occult blood test?

Your doctor may recommend a faecal occult blood test (FOBT) if you are over 50 years old, have a family history of bowel cancer, or if you have unexplained anaemia. This test is also used as a routine check to help find bowel cancer early, when treatment works best.

If you already have symptoms such as blood in your stool or big changes in your usual bowel habits, your doctor may suggest a different test, such as a colonoscopy, to look directly inside your bowel instead.

How do I prepare for the test?

How you get ready for the test depends on the type of faecal occult blood test (FOBT) you are having.

• Immunochemical FOBT (iFOBT or FIT):

  • Usually, you don’t need to change your diet or stop taking medicines before this test.

• Guaiac FOBT (gFOBT):

  • You may be asked to avoid certain foods and medicines for a few days before the test, as they can affect the results.

  • These may include red meat, some raw fruits and vegetables, vitamin C tablets, iron tablets, and painkillers such as aspirin and ibuprofen. Eating or taking these before the test might give a wrong result.

Always follow the instructions given by your doctor, nurse, or the test kit. If you’re not sure about anything, it’s best to ask your healthcare provider before starting the test.

What happens during a faecal occult blood test?

Your healthcare provider typically provides a kit for you to use at home during the stool test. The process usually involves:

• Collect small samples of stool from different bowel movements, often over three separate days

• Transfer a small amount of stool onto a test card or into a collection tube using the spatula, stick, or applicator provided

• Seal the samples and send them back to your healthcare provider or laboratory for testing

• The laboratory checks the samples for the presence of hidden blood

The kit typically includes everything you need to complete the test and instructions to explain the process. For best results, follow the instructions that come with your test kit.

What do the results mean?

After your samples are tested, your doctor will explain the results. The results show whether or not there is hidden blood in your stool, and what this might mean for your health.

• Negative result:

  • No blood was detected in your stool. This is considered normal, but regular screening may still be recommended if you are at average risk for bowel cancer.

• Positive result:

  • Blood was found in your stool. This does not necessarily mean you have cancer. Other possible causes include polyps, haemorrhoids, ulcers, diverticular disease, or inflammatory bowel disease. Further tests, such as a colonoscopy, will be needed to find the source of the bleeding.

False positives and false negatives can happen, especially if the preparation instructions were not followed correctly.

Are there any risks to the test?

A faecal occult blood test (FOBT) is very safe, and there are no physical risks from collecting stool samples at home. However, the test is not perfect. It may miss some cases of bowel cancer or other conditions, and it can sometimes give a false-positive or false-negative result, which might lead to unnecessary tests or missed diagnoses.

Your doctor can help you understand the benefits and limitations of the test and decide whether an FOBT is suitable for you, based on your own health and risk factors.

If you’re considering a faecal occult blood test, schedule an appointment with Thomson Medical. Our specialists can run through the pros and cons of the test with you, explain your personal risk factors, and help you decide on a screening plan.

FAQ

What does a faecal occult blood test look for?

A faecal occult blood test (FOBT) looks for hidden blood in the stool, which may be a sign of bleeding in the digestive tract due to conditions such as polyps, cancer, ulcers, or inflammatory bowel disease.

What happens if the faecal occult blood test result is positive?

If the test is positive, your healthcare provider will usually recommend further investigations, most commonly a colonoscopy, to identify the source of the bleeding and determine if it is due to a serious condition such as cancer or a more benign cause like haemorrhoids.

What is the most common cause of occult blood in stool?

The most common causes of occult blood in stool include benign or malignant growths (polyps or cancer), haemorrhoids, ulcers, diverticular disease, and inflammatory conditions of the bowel.

Can a faecal occult blood test detect cancer?

A faecal occult blood test is used as a screening tool for colorectal cancer. While it can detect hidden blood that may be caused by cancer, it cannot diagnose cancer directly. A positive result requires further testing to confirm the diagnosis.

Can faecal occult blood be cured?

Occult blood is not a disease itself. It is a sign that something is happening in the bowel. Treatment depends on the cause. Once the cause (such as polyps, ulcers, or haemorrhoids) is treated, the bleeding and the occult blood usually stop.

Can faecal occult blood testing detect all colorectal cancers?

Faecal occult blood tests is a screening tool for bowel (colorectal) cancer. It can detect hidden blood that may be caused by cancer, but it cannot diagnose cancer directly. A positive result always requires further tests to confirm the cause.

Are there alternatives to the faecal occult blood test for colorectal cancer screening?

Yes, there are other screening options. These include colonoscopy, sigmoidoscopy, and stool DNA tests. Your doctor can help decide which test is most suitable based on your risk factors and preferences.

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice based on your unique situations, please consult a specialist at Thomson Medical. Schedule an appointment with Thomson Medical today.