Faecal Immunochemical Test ( FIT )

Faecal immunochemical test ( FIT ) test uses antibodies that specifically recognises human haemoglobin

replaced FOB ( Guaiac faecal occult blood test gFOBt ) as primary test for NHS bowel screening program me in 2016 sensitivity to pick up CRC was significantly better in NICE modeling more specific than gFOBt useful in both screening and symptomatic assessment applications greater accuracy in detecting of CRC in symptomatic patients in gHOBt 2 sample from 3 stools were needed whereas FIT requires only 1 stool sample from a single bowel motion
( ie easier to use -better uptake ) no dietary interference ie no false positives if patient eats meat whereas in gFOBT false positive results could be seen with upper GI bleeding – this is not the case with FIT FIT can detect cancers at an early stage , particularly adenomas

Refer to secondary care along side +/- FIT
 aged 40 and over with unexplained weight loss & abdominal pain OR aged 50 and over with unexplained rectal bleeding OR aged 60 and over with IDA ( Iron deficiency anaemia ) or CIBH ( change in bowel habit ) positive faecal occult blood a rectal or abdominal mass aged < 50 with rectal bleeding and any of the following unexplained symptoms or findings
○ abdominal pain
○ CIBH
○ weight loss
○ IDA

Please request FIT ( these are the patient who are not meeting the criteria for a suspected cancer referral as outlined in NG 12 ie low risk but not no risk patients ) 

 aged 50 and over with unexplained weight loss or abdominal pain aged under 60 with CIBH OR IDA aged 60 and over with anaemia even in absence of IDA

Standard bloods FBC , CRP , TFT , Haematenics , LFTs , Coeliac serology , if diarrhoeal and < 50 consider faecal calprotectin

use clinical judgement – small number of CRC’s would be missed ie false negatives & negative tests do not guarantee that it is not cancer safety net & advice to remain vigilant for ongoing / worsening symptoms abdominal pain can also be presentation of other cancers as gynaecological / pancreatic and FIT would be – ve important to understand that FIT for screening is quantitative and the threshold for an abnormal result is set locally ie if a patient had a recent national screening FIT which was negative , once symptomatic the new test is valuable & may be positive as a different cut-off may be used for asymptomatic screening if despite negative test a clinical concern remains around cancer – refer for assessment FIT should not be used in younger patients in whom you suspected inflammatory bowel disease – use faecal calprotectin

REFERENCES

1. *Faecal immunochemical testing in general practice (faecal-immunochemical-test.co.uk)
2.  Clinical need and practice | Quantitative faecal immunochemical tests to guide referral for colorectal cancer in primary care | Guidance | NICE
3. Questionnaire: USC FIT for symptomatic referrals – Public Health Wales (nhs.wales)
4. *Faecal-Immunochemical-Testing-FIT.pdf (mft.nhs.uk)
5. Introduction of FIT as a Primary Care Diagnostic Tool *Information Leaflet.pdf (rotherhamccg.nhs.uk)