Understanding the qFIT test

Rates of bowel cancer are on the rise among younger adults, and it’s not overly clear why. Now, around one in 20 cases in the UK are diagnosed in under-50s. 

As a result, many are taking better care of their bowel health and turning to screening tests like the qFIT to detect the condition before symptoms appear. The quantitative faecal immunochemical test (qFIT) is a simple, at-home test that checks for traces of blood in the stool. 

While it’s not suitable for everyone and can’t replace medical advice, it’s a helpful tool for people at higher risk or looking for reassurance. In this article, we discuss the pros and cons of testing as well as what your results might mean. 

• What is the qFIT test? 
• What’s the difference between the FIT, qFIT, and FOB test? 
• How accurate is the qFIT test? 
• Should I take a qFIT test? 
• When is the qFIT test not appropriate? 
• What does a positive qFIT result mean? 

What is the qFIT test?

The qFIT test is a simple at-home test that checks for tiny traces of blood in your stool that you wouldn’t notice yourself. It measures the level of a protein called haemoglobin, which is found in blood.

Hidden blood can sometimes be an early sign of bowel problems, like colorectal cancer. The test is quick, easy, and reliable and is like the one used in the NHS Bowel Cancer Screening Programme.

You can buy a qFIT test with Medichecks to take in the comfort of your own home, which comes with a bespoke doctor's report on what to do next with your results.
 

What’s the difference between the FIT, qFIT, and FOB test?

The key difference between the FIT test and the qFIT test is how results are reported:  

• The FIT test is qualitative, providing a simple positive or negative result based on whether blood exceeds a set threshold.  
• The qFIT test is quantitative, measuring the exact amount of blood (haemoglobin) in the stool, reported in µg Hb/g, allowing for more precise and personalised decision-making.  
• The FOB (faecal occult blood) test is still used for surveillance purposes, but in many cases, it’s been replaced by the FIT/qFIT test. That’s because the qFIT test is more accurate, with fewer false positives, and is unaffected by diet. 

Whether you’re worried because of your family history, have mild symptoms, or just want peace of mind, this test is a helpful way to keep an eye on your bowel health. 
 

How accurate is the qFIT test?

The qFIT test detects blood in the stool but it can’t diagnose bowel cancer. If blood is detected, there’s about a 10% chance that bowel cancer will be detected with further tests. More often, other conditions are the cause of a positive result. 

A negative result is reassuring. With a result of less than 10 μgHb/g, your chance of having cancer is 0.1% (1 in 1000). 
 

Should I take a qFIT test?

The qFIT test is an effective screening tool and can help pick up bowel conditions before symptoms appear. But before you decide, it’s worth weighing up the pros and cons of the test. 

Benefits of the qFIT test include: 

• Catches problems early — it can detect bowel cancer or other issues before they cause serious symptoms.
• Convenience — you can take the test in the comfort of your own home.
• Fewer invasive procedures — it might reduce the need for more uncomfortable tests, like a colonoscopy, if the result is negative.
• Peace of mind — a negative result can be reassuring and reduce anxiety.
• Supports GP assessment — it helps GPs figure out who needs more urgent specialist referrals.
• Helpful for high-risk groups — for people with a strong family history of bowel cancer, this is a great way to screen for the condition.

Risks of the qFIT test include: 

• False positives — about 9 in 10 people with a positive result don’t have bowel cancer. This can lead to follow-up tests like colonoscopy, which can be stressful and carry small risks such as bleeding or bowel perforation. But other important bowel conditions are sometimes picked up.
• False negatives — Rarely, the test might miss small amounts of blood. This happens in about 1 in 1000 cases (with a result of <10 μgHb/g), meaning it’s very unlikely but possible. Missing early signs of cancer can delay diagnosis.
• Overdiagnosis — The test might find non-serious conditions or small, slow-growing cancers that wouldn’t have caused harm, leading to unnecessary treatments.
• Anxiety or reassurance — A positive result can cause unnecessary worry, while a negative result might provide false reassurance in very few cases, particularly if symptoms develop later.

The NICE Clinical Knowledge Summary (CKS) on bowel screening highlights these potential harms and emphasises the need for informed decision-making. 
 

When is the qFIT test not appropriate?

The qFIT test is a helpful test for detecting hidden blood, but it’s not for everyone. If you notice any of the following symptoms, skip the qFIT test and see your GP urgently. 

See your GP if you notice: 

• A sensation of a lump or sore in the rectum or anus 
• Blood you can see in your stool — visible blood should be discussed directly with your doctor as you may need an examination. 
• New urgency or a feeling of needing to strain in your back passage, even after opening your bowels 
• A sudden new change in bowel habits — either constipation or diarrhoea
• Dramatic unexpected weight loss 

Severe symptoms, such as feeling generally very unwell, severe stomach pain, or large amounts of rectal bleeding require an urgent same-day medical assessment. 
 

What does a positive qFIT result mean?

If your result is positive, it means blood was found in your stool. Don’t panic — most positive results are not because of bowel cancer. But it does mean your doctor will likely ask you to repeat the test or recommend further tests, like a colonoscopy, to find out what’s causing the bleeding. 

Other common causes of a positive qFIT test include:

• Haemorrhoids (piles)
• Inflammation (like Crohn’s disease or ulcerative colitis)
• Stomach ulcers
• Benign (non-cancerous) polyps
• Contamination if you’re on your period
• Diverticular disease

Interpreting results – what is a positive qFIT result?

We use different thresholds to determine whether a qFIT result is positive or negative, based on whether you have symptoms of bowel cancer. That’s because having symptoms of bowel cancer raises the probability of having it, so there is a lower threshold for referring someone to have further tests. 

If you don’t have symptoms:

• A result above 80 µg Hb/g (or 120 µg Hb/g depending on where you live) is considered positive. The UK thresholds for NHS bowel screening programme are applicable for those without symptoms.

If you do have symptoms:

• A result over 10 µg Hb/g is considered positive and means you may need further tests, even if your symptoms seem mild.

Important note: Even if you’ve had a negative FIT result through the NHS Bowel Screening Programme, you should take another test if you develop symptoms. This is because the screening programme uses a higher threshold to detect blood than tests for symptomatic individuals. A qFIT test for symptoms is more sensitive and designed to pick up smaller amounts of blood.

In both cases, a positive result doesn’t mean you have bowel cancer, but it does mean you should talk to your doctor for follow-up tests.

Take control of your health

The qFIT test is a simple way to stay proactive about your health. While it’s not a replacement for medical advice nor diagnostic, it’s a helpful tool for early detection and peace of mind. If you’re worried about your bowel health or have a family history of bowel cancer, this test could be a great starting point.

References

1. Potential harms with screening | Background information | Bowel screening | CKS | NICE. [cited 16 Dec 2024]. Available: https://cks.nice.org.uk/topics/bowel-screening/background-information/potential-harms-with-screening/