FIT (Faecal Immunochemical Test)

Overview

The Quantitative Faecal Immunochemical Test (qFIT) is a test to detect hidden or ‘occult’ blood in stool samples. Unlike older FOB tests, qFIT uses antibodies that specifically recognise human haemoglobin which makes it a more sensitive and specific test than the guaiac based FOB test. 

As a quantitive test it also allows the amount of haemoglobin to be measured.

The qFIT requested for patients with symptoms has a much lower threshold for a positive result than the qFit done as part of the routine NHS Bowel screening program (10 μgHb/g vs 120 μgHb/g for a positive result) and as such a negative bowel screening test does not remove the need to repeat a qFit for a symptomatic patient.

See the Potting the poo: getting the right (FIT) poster (2) for a summary of the available tests.

When to request a qFIT

2WW symptoms

• Aged 40 and over with unexplained weight loss and abdominal pain
• Aged 60 and over with changes in bowel habit
• Aged 50 and over with unexplained rectal bleeding
• Aged under 50 with rectal bleeding and any of the following unexplained symptoms or findings: abdominal pain, change in bowel habit, weight loss, iron-deficiency anaemia

Low risk but not no risk symptoms (unexplained)

• Aged under 60 with iron deficiency anaemia
• Aged 60 and over with non-iron deficiency anaemia
• Aged 50 or over with abdominal pain or weight loss
• Aged over 18 with change in bowel habit or other symptoms that could be attributable to colorectal cancer.

Non-specific symptoms

• Patients who meet the criteria for the Non-specific Symptoms - Fast Track Service should have a qFit as part of the filter function tests.

Colorectal 2WW symptoms not requiring a positive qFIT for referral

The qFIT is not currently required in the following patients who can continue to be referred via the lower GI - USC (2WW) pathway without this result

• Rectal mass
• Abdominal mass
• Unexplained anal mass or unexplained anal ulceration
• Aged 60 and over with an iron deficiency anaemia

If unable to complete a qFIT

These patients should be managed according to national guidance and can still be referred on a colorectal - USC (2WW) pathway if indicated, but to an outpatient appointment rather than straight to test.

Administering the test

To request a test complete the request on ICE, label the collection kit and hand this to the patient for completion at home.

There is a risk that patients will not appreciate the importance of carrying out a FIT and how crucial the result will be to decisions on their management. GPs are therefore encouraged to emphasise the need for the test to be completed and sent off quickly.

 It is advisable to have a method of safety-netting so that patients who have not returned their test can be followed up.

Please highlight that only a small sample of stool is needed (as per the enclosed leaflet) and that if the patient has rectal bleeding to take the sample from an area of stool with no blood visible on the surface as the test is looking for blood mixed in with the stool.

The test is available to request on ICE. Please follow the usual process for sending samples to the lab ensuing it is labelled with the ICE sticker (placed vertically so the barcode can be scanned) and returned with the request form.

Give the pack to the patient and advise them to read the instructions carefully before completing the test and returning the kit to the practice to be sent off.

Samples will only be processed if received in the correct FIT kit, please do not send samples in the blue topped containers as these will not be processed (2). Please send completed sample pots to the laboratory in their own sample bag to ensure that they are processed promptly.

qFit requests can be recorded on EMIS using the read code 4791 (Faecal Occult Blood Requested) on your clinical system (SNOWMED ID 167666002).

Consider having a process to chase up kits that have not been collected or haven’t been returned. There is an accurx template that can support with this as well as an Ardens safety-netting template.

Results and referral

Positive qFIT (>10)

Refer on a colorectal 2WW pathway, straight to test where appropriate. This should happen promptly upon receipt of the result.

Negative qFIT (<10)

A negative qFIT with a normal examination and normal full blood count means that the patient has a less than <0.1% risk of having colorectal cancer.

These patients should be reviewed in primary care with consideration given to alternative diagnosis and referral on another pathway if appropriate. If the decision is made not to refer, then they should be given appropriate safety-netting information.

Please also see qFIT negative – suggested next steps

Patients can still be referred on a 2WW colorectal pathway if qFIT negative if there is significant clinical concern that the most likely diagnosis is a colorectal cancer. These patients should be referred using ERS for an outpatient appointment rather than STT route (Straight To Test)

Ongoing symptoms after investigation

If a qFIT is positive and the secondary care investigative test is negative indicating no colorectal cancer then the secondary care advice is not to repeat the qFIT or re-refer on a colorectal 2ww pathway (assuming investigative test performed based on a positive qFIT is of adequate quality and the endoscopist or radiologist is happy with the quality of the test).

Consider other potential causes of the patient’s symptoms that led to a qFIT being requested and if there is ongoing concern then the patient can be referred on routine or urgent non-2WW pathway to colorectal surgery or gastroenterology as clinically indicated.

Resources

(1) Key things to know about FIT - advice for health professionals from Cancer Research UK.

(2) Potting the poo: getting the right (FIT) poster - making sure you use the correct test.

(3) Faecal immunochemical testing (FIT) in patients with signs or symptoms of suspected colorectal cancer (CRC): a joint guideline from the Association of Coloproctology of Great Britain and Ireland (ACPGBI) and the British Society of Gastroenterology (BSG)

(4) Referral for suspected gastrointestinal tract (lower) cancer | Management | Gastrointestinal tract (lower) cancers - recognition and referral | CKS | NICE

(5) A cohort study of duplicate faecal immunochemical testing in patients at risk of colorectal cancer from North-West England. BMJ Open 2022;12:e059940. doi:10.1136/bmjopen2021-05994

(6) Using the faecal immunochemical test in patients with rectal bleeding: evidence from the NICE FIT study - PubMed (nih.gov)

(7) Using Faecal Immunochemical Testing (FIT) in the Lower Gastrointestinal (GI) pathway_ Primary Care letter_061022) (6th of October 2022)

Efforts are made to ensure the accuracy and agreement of these guidelines, including any content uploaded, referred to or linked to from the system. However, BNSSG ICB cannot guarantee this. This guidance does not override the individual responsibility of healthcare professionals to make decisions appropriate to the circumstances of the individual patient, in consultation with the patient and/or guardian or carer, in accordance with the mental capacity act, and informed by the summary of product characteristics of any drugs they are considering. Practitioners are required to perform their duties in accordance with the law and their regulators and nothing in this guidance should be interpreted in a way that would be inconsistent with compliance with those duties.

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