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Evidence-led screening guide

FIT Test

A faecal immunochemical test, usually called a FIT, checks a small stool sample for tiny amounts of blood that may not be visible. FIT is used in NHS bowel cancer screening and may also be requested by a clinician when someone has certain bowel symptoms.

Read the official NHS screening FIT kit instructions (external link, opens in a new tab)Read Our Guide
A Black man reading home test instructions in a warmly lit living room

Quick guide

FIT Test at a Glance

What FIT stands for
Faecal immunochemical test.
What it checks for
Tiny amounts of human blood in a stool sample. FIT does not look for cancer directly.
How the sample is collected
At home, using the sampling stick and container supplied with the kit. Always follow the instructions for your specific kit.
Why it may be used
As part of bowel cancer screening for eligible people without symptoms, or when a clinician requests it to help assess certain bowel symptoms.
What an abnormal result may lead to
Further assessment or investigation within the screening or clinical pathway in which the test was requested.
What a normal result does not guarantee
FIT does not diagnose cancer, and a normal result does not completely rule bowel cancer out. Persistent or concerning symptoms still need medical assessment.

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2. What Is a FIT Test?

FIT stands for faecal immunochemical test. It checks a small sample of stool for tiny amounts of human blood that may not be visible. The test responds to human haemoglobin, a protein found in blood.

FIT does not look for cancer cells. Polyps and bowel cancers can bleed, but blood in stool can also have other causes. A FIT result therefore helps decide what should happen next; it is not a cancer diagnosis.

This guide primarily describes England. Screening programmes and clinical pathways differ across the UK, so follow the instructions and official guidance for the nation and service that supplied your kit.

3. Why Is FIT Used?

FIT is used because a small stool sample can provide useful information about possible bleeding in the bowel. It can be completed privately at home and analysed in a laboratory.

In the NHS bowel cancer screening programme, FIT is offered to eligible people who do not have symptoms. The purpose is to identify people who may need further investigation. A clinician may also request FIT when a person has certain bowel symptoms, to help decide the safest next step alongside their symptoms, history and examination.

Learn more about the population programme in the NHS Bowel Cancer Screening guide.

4. Screening FIT and Diagnostic FIT: What Is the Difference?

Screening FIT

Screening FIT is part of a population programme for eligible people who do not have symptoms. The screening programme sets its own threshold, result wording and follow-up pathway. In England, the programme sends the kit and communicates the result.

Clinician-Requested FIT

A GP or another clinician may request FIT to help assess certain bowel symptoms. This is often called symptomatic or diagnostic-pathway FIT, although FIT itself does not make a diagnosis. The clinician interprets the result alongside other clinical information and current referral guidance.

The laboratory method may be similar, but the purpose, thresholds and pathways are not interchangeable. Do not compare a number from one pathway with information written for another. Follow the advice from the service that requested your test.

5. How to Complete a FIT Sample

Different services may supply different kits, so always read the instructions that came with yours. For the NHS bowel screening kit used in England, the official steps are:

  1. Write the requested date on the sample bottle.
  2. Use a clean container or layers of toilet paper to catch the stool before it touches toilet water.
  3. Twist open the sample bottle and scrape the sampling stick along the surface of the stool until the grooves are covered. Only a small amount is needed.
  4. Put the stick back into the bottle and click the cap closed. Do not reopen it.
  5. Wash your hands, check the date is recorded, seal the bottle in the supplied return envelope and post it as soon as possible.

If your GP or another service supplied the test, use their labelling and return instructions. Contact the supplying service if the kit is lost, damaged, out of date or difficult to use.

Follow the official NHS bowel screening FIT kit instructions for England (external link, opens in a new tab)

6. What a FIT Result May Mean

Result wording and next steps depend on whether the test came from the screening programme or was requested by a clinician.

Screening Result: No Further Tests Needed at This Time

This means no blood was found, or the amount was below the screening programme threshold. It does not guarantee that you do not have bowel cancer. If you remain eligible, the programme will usually invite you again at the normal interval.

Screening Result: Further Tests Needed

This means blood was found at or above the programme threshold. It is not a cancer diagnosis. The screening programme will arrange contact to discuss the result and further assessment, which may include a colonoscopy.

Clinician-Requested FIT Result

Your clinician should interpret the result with your symptoms and other clinical information. A result below the referral threshold does not override ongoing clinical concern. A result at or above the relevant threshold may lead to urgent referral or other investigation, depending on the pathway.

Sometimes a test cannot be processed and another sample is needed. Follow the message from the screening programme, laboratory or clinician.

7. Benefits of FIT

  • It needs only a small stool sample and can usually be completed privately at home.
  • Nothing is inserted into the body to collect the sample.
  • In screening, it helps identify people who may benefit from further investigation before symptoms appear.
  • In symptomatic pathways, it can help clinicians assess who may need urgent investigation when used with clinical information.
  • It measures human blood, which reduces interference from food compared with older stool blood tests.

8. Limitations and Possible Harms

FIT is useful, but it is not completely accurate and cannot be interpreted safely in isolation.

  • A normal result can be falsely reassuring: a polyp or cancer may not bleed when the sample is collected.
  • An abnormal result does not identify the cause: bleeding can come from cancer, polyps, haemorrhoids or other conditions.
  • Further tests may cause anxiety or harm: an abnormal result can lead to investigations such as colonoscopy, which has benefits and risks that should be explained before consent.
  • Pathways use different thresholds: applying screening information to a clinician-requested result, or the reverse, can be misleading.
  • Sample or handling problems can affect processing: another kit may be required if the sample cannot be analysed.

9. Symptoms and When to Contact Your GP

Contact your GP about bowel changes or symptoms that persist, change or worry you. These can include blood in your stool or bleeding from your bottom, a change in bowel habit, tummy pain or bloating, unexplained weight loss, or unusual tiredness that may relate to anaemia.

Symptoms can have many causes and do not necessarily mean cancer. However, a screening invitation is not a route for assessing symptoms, and a normal FIT result does not replace clinical review if symptoms continue.

For wider symptom-awareness information, read the Cancer Symptoms guide.

Read current NHS bowel cancer symptoms and urgent-action advice (external link, opens in a new tab)

10. Common Myths About FIT

“A positive FIT means I have bowel cancer.”

No. It means blood was detected at a level that requires action in that pathway. Further assessment is needed to find the cause.

“A normal FIT means I definitely do not have bowel cancer.”

No. FIT can miss bleeding, and not every cancer bleeds all the time. Persistent or concerning symptoms still need medical assessment.

“Screening FIT and diagnostic FIT are exactly the same.”

No. They are used for different groups and purposes, and their thresholds, result wording and follow-up pathways may differ.

“I should wait for a screening kit even though I have symptoms.”

No. Contact your GP. Routine screening is intended for people without symptoms and must not delay clinical assessment.

11. Frequently Asked Questions

What does FIT stand for?
FIT stands for faecal immunochemical test. It is a laboratory test that checks a small stool sample for tiny amounts of human blood that may not be visible.
What does a FIT test check for?
FIT checks for human blood in stool. It does not look for cancer cells and cannot diagnose cancer. Blood can have several causes, so the result must be interpreted in the pathway in which the test was requested.
Does an abnormal FIT result mean cancer?
No. An abnormal result means that blood was detected at a level that needs action within that screening or clinical pathway. Conditions other than cancer can cause bleeding, and further assessment is needed to find the cause.
Can a normal FIT result miss bowel cancer?
Yes. A normal result does not completely rule out bowel cancer because a cancer or polyp may not be bleeding when the sample is collected. Contact your GP if symptoms persist, change or concern you, even after a normal result.
Is the FIT test painful?
No. You collect a small sample from a bowel movement using the sampling stick supplied. Nothing is inserted into your body.
How do I collect the sample?
Follow the instructions supplied with your kit. For the NHS screening kit in England, you catch the stool before it touches toilet water, scrape the sampling stick along its surface until the grooves are covered, click the stick back into the bottle, write the date as instructed, seal the return envelope and post it promptly.
Can piles or haemorrhoids affect a FIT result?
Piles can bleed and may be one possible cause of blood in stool. Do not assume that piles explain a result or symptom. Follow the advice that comes with your result and contact your GP about bleeding or other concerns.
Can I complete a FIT test during my period?
For the NHS bowel screening kit in England, official guidance says it is best to collect the sample when you are not having a period and to avoid the two days before or after bleeding. For a clinician-requested FIT, follow the instructions from the requesting service or ask them when to collect the sample.
What should I do if I lose or damage the kit?
If it is an NHS bowel screening kit in England, call the free bowel cancer screening helpline on 0800 707 60 60 for help or a replacement. If a GP or another clinician requested the test, contact the service that supplied it.
Is screening FIT the same as a FIT requested by my GP?
The laboratory method may be similar, but the purpose, threshold, result wording and follow-up pathway can differ. Screening FIT is offered through a population programme to eligible people without symptoms. Clinician-requested FIT helps assess certain symptoms and must be interpreted alongside clinical information.
How will I receive the result?
The NHS bowel screening programme in England sends screening results by letter. For a clinician-requested FIT, the requesting GP or service should explain how and when the result will be communicated. Contact that service if you are unsure.
What should I do if I have symptoms?
Contact your GP rather than waiting for a routine screening invitation or kit. A screening test is not a substitute for medical assessment, and persistent or concerning symptoms still need review even after a normal FIT result.

12. Evidence and References

These primary sources were selected for authority, relevance and currency. The guide avoids a single numerical FIT threshold because screening and symptomatic pathways use different thresholds and programme arrangements can change.

13. Official NHS Resources

Use these official sources for current screening instructions, programme arrangements, results and support in England.

14. How BloomShield Helps

Clear information is one part of equitable access. BloomShield’s connected programmes support understanding, practical access and navigation across screening and care pathways.

ScreenAccess™

identifies and helps address practical, social and service barriers to screening access.

ScreenConnect™

supports navigation, coordination and continuity across screening and care pathways.

Work with BloomShield to improve screening access