Private bowel screening versus the NHS FIT kit

The NHS kit came through the letterbox, you did the sample, and the letter said no further tests needed. Or you're in your forties and nothing has arrived yet, or you'd simply like a doctor to look at the whole picture rather than one envelope.

Both have a place. The NHS FIT kit is a good screening test for hidden blood in the stool. A private bowel package adds what an envelope can't: a doctor who takes your history, blood tests for iron and anaemia, and an inflammation marker. At the higher tier you also get a CT scan of the bowel, reviewed with a colorectal surgeon.

If you'd rather skip the reading, the Essential bowel screen is £499 at our Harley Street clinic, with most results in three to five working days and no GP referral needed. The Health Screening Clinic has done doctor-led screening at 117a Harley Street since 1984 and is CQC registered.

If you have rectal bleeding, black stools, a lump in the abdomen or rectum, unexplained weight loss, or a bowel habit that has changed and stayed changed, see your GP the same day. NICE suspected-cancer guidance (NG12) treats those symptoms as a reason to investigate now, so take an urgent referral if you're offered one. Call 999 or go to A&E if you're collapsing, in severe pain or bleeding heavily.

How the NHS FIT kit works

NHS bowel cancer screening is a home test for people aged 50 to 74. If you're registered with a GP, a faecal immunochemical test (FIT) kit arrives by post every two years. You scrape a small sample of faeces onto a stick, post it back, and usually get a letter within two weeks. If you're 75 or over, you can ask for a kit on 0800 707 6060.

The UK National Screening Committee recommended the programme, including the expansion down to age 50, because the evidence showed more benefit than harm. The test looks for hidden blood, which can come from a polyp, from cancer, from piles, from a small tear (a fissure), or from nothing that will ever matter. NHS.uk is clear that a letter asking for further tests doesn't mean you have cancer. Equally, a letter saying no further tests are needed doesn't rule out bowel cancer now or later.

Screening works within limits. The UK NSC describes it as identifying apparently healthy people who may have a higher chance of a condition. Tests offered to large groups tend to be simple rather than very accurate, and they often lead to further tests. That's true of private tests too.

Why the same FIT can have two different cut-offs

This is the part that catches people out. FIT measures the amount of haemoglobin in the sample, and the cut-off depends on why you're being tested.

For people who already have symptoms, such as a change in bowel habit, iron-deficiency anaemia or unexplained rectal bleeding, NICE NG12 draws on its HealthTech guidance on quantitative FIT in primary care. It uses a threshold of 10 micrograms of haemoglobin per gram of faeces to guide urgent referral. If your GP asked you for a FIT because of symptoms, it's this kind of test.

The NHS screening programme in England has used a much higher threshold, 120 micrograms per gram. The UK NSC recommended lowering it to 80, and NHS England is rolling that change out in phases, aiming to finish by March 2028. Wales and Scotland already use 80. So a clear screening letter answers a different question from a symptom test, and new symptoms are always worth taking to your GP.

What happens after a positive FIT?

A positive screening FIT means blood was found above the threshold. You're then invited to see a specialist nurse and, usually, to have a colonoscopy, which looks directly at the bowel lining and can remove polyps. A negative result means hidden blood wasn't found above the threshold in that sample, so keep doing the kit each time it comes.

What the private bowel packages add

Private bowel screening is a doctor-led package built around your history, your bloods and, at Elite, imaging.

The Essential bowel screen costs £499. It includes a consultation with a lifestyle and risk assessment, quantitative FIT with calprotectin, a blood panel that includes iron and haemoglobin, and an in-person review. Most results are ready in three to five working days. Calprotectin is an inflammation marker, used more for bowel inflammation than as a cancer test, and it can be raised by inflammatory bowel disease, infection and other non-cancer causes. Iron and haemoglobin can show anaemia, which NICE already treats as a reason to look at the bowel. A flag on any of them means looking again with your history and, if needed, with pictures.

The Elite bowel screen costs £2,499. It keeps the consultation, QFIT and calprotectin, then adds enhanced bloods with CEA, CRP, full iron studies, B12, folate and a metabolic panel. It also adds expanded stool tests (FIT, FOBT, calprotectin and elastase when requested), CT colonography and a same-day colorectal surgeon. FOBT is an older blood-in-stool method, and elastase looks at how much digestive enzyme the pancreas produces. CEA is used mainly in people already known to have bowel cancer, rather than as a population screen.

A private package is useful if you're under 50, over 74 or between invitations, and it works alongside the NHS programme. If you're eligible, keep posting the kit.

Colonoscopy and CT colonography: what's the difference?

Optical colonoscopy passes a camera through the bowel. It's the investigation that can take a biopsy and remove a polyp there and then. CT colonography images the colon from outside, without a camera inside the bowel. It uses ionising radiation, can miss flat lesions, and sometimes finds things outside the colon that then need explaining.

On Elite, a radiologist reports the scan and the colorectal surgeon reads that report alongside your stool tests and bloods. The package is priced and designed as a screen rather than an optical colonoscopy.

Does a Health MOT check the bowel?

A Health MOT is a wide preventative assessment. Every tier includes a GP examination, bloods, a report and a review, but none of that is a dedicated bowel protocol. CEA on an Elite MOT is a marker rather than a FIT, and full-body MRI on Ultimate gives only a weak look at the bowel lining. If the bowel is your question, a bowel package is the better fit, and it can sit beside a MOT. Either way, the doctor who took your history decides whether a result needs repeating, watching, imaging or referral.

Getting ready

• Complete the NHS sample as its leaflet describes, whenever a kit arrives.
• Bring previous FIT letters, colonoscopy reports and iron studies.
• Tell the doctor about any symptoms first, before choosing a package.
• Ask which stool tests you're having, and whether CT colonography is part of your booking.
• Allow three to five working days for results, and keep the review.

To see both packages, visit the bowel cancer screening page, book online or call The Health Screening Clinic on 020 7183 7056.

For why a CEA blood test isn't a bowel screen, read can a blood test detect cancer. For choosing between organ packages and wider screening, see whole-body cancer screening versus an organ package.

Frequently asked questions

Is private bowel screening a replacement for the NHS FIT kit?

It works alongside it. The NHS programme sends a home kit every two years to people aged 50 to 74. A private package adds a doctor, bloods, calprotectin and, at Elite, CT colonography and a colorectal surgeon. Keep doing the NHS kit if you're eligible.

I have rectal bleeding or unexplained weight loss. What should I do?

See your GP the same day, and take an urgent referral if you're offered one. NICE NG12 treats those symptoms as a reason to investigate now. Call 999 or go to A&E in an emergency.

Does a negative FIT mean I do not have bowel cancer?

Not always. NHS.uk says a result of no further tests needed doesn't always mean you don't have bowel cancer, and it doesn't stop you getting it later. Get new symptoms checked, even after a reassuring letter.

What does the Essential bowel package include?

It costs £499 at 117a Harley Street and includes a consultation, quantitative FIT with calprotectin, bloods including iron and haemoglobin, and an in-person review. Results are usually ready in three to five working days, and the doctor explains any flag.

What does Elite add?

Elite costs £2,499. It adds enhanced bloods including CEA, CRP, iron studies, B12, folate and a metabolic panel, expanded stool tests (FIT, FOBT, calprotectin and elastase when requested), CT colonography and a same-day colorectal surgeon. It's designed and priced as a screen rather than an optical colonoscopy.

Is CEA a bowel cancer blood test I can rely on?

Not on its own. CEA can be raised for non-cancer reasons and normal in early bowel cancer. NICE uses it mainly to follow up known disease, and the NHS programme uses a stool FIT instead.

Do I need a GP referral?

No. You can book yourself in at 117a Harley Street, where the clinic has been doctor-led since 1984 and is CQC registered. If you have symptoms, see your GP as well.

Sources

• NHS. Bowel cancer screening
• UK National Screening Committee. Principles of screening
• UK National Screening Committee. More sensitive bowel cancer screening test implemented
• NICE. Suspected cancer: recognition and referral (NG12)
• NICE. Quantitative faecal immunochemical testing to guide colorectal cancer pathway referral in primary care
• GOV.UK. NHS bowel cancer screening programme
• General Medical Council. Medical register, Penelope Sheehan, 6056535

Written By

Stephen Lingam

Managing Director

Managing Director of Medical Express Clinic and the Health Screening Clinic since 1984. Over 40 years of operational experience in private healthcare on Harley Street, overseeing patient care, clinical standards, and service delivery.

Medically Reviewed

Dr Penny Sheehan

MBBS, MRCGP

General Practitioner

GMC: 6056535

Specialising in women's health, hormonal balance, and menopause management within screening contexts.

Last reviewed: 25/09/2026