ColoAlert Results Explained: Positive, Negative and What Happens Next

ColoAlert results explained: positive, negative and what happens next

You sent off a stool sample, waited a few weeks, and now you’ve got a result back. Whether it says positive or negative, the next question is the same: what does this actually mean, and what do I do about it?

This guide walks through every possible ColoAlert result, what it tells you, and what the next step should be. Written by the doctor who brought the test to the UK.

How ColoAlert works in 60 seconds

ColoAlert looks at your stool sample for two things:

1. Human haemoglobin (blood) — the same thing the NHS FIT test looks for

2. DNA changes that cancer cells and large polyps shed into your stool — KRAS mutations, BRAF mutations, and DNA methylation patterns

Together, these are far more sensitive than blood alone. ColoAlert detects around 85% of colorectal cancers and around 40% of advanced adenomas (the polyps that turn into cancer) — significantly better than FIT alone.

The result you get back is a combined assessment of these markers.

A negative ColoAlert result

What it means: No significant blood or DNA cancer markers detected in your sample at this time.

What it doesn’t mean: - “You don’t have bowel cancer” — no screening test is perfect. About 15% of cancers don’t shed detectable markers - “You’ll never have bowel cancer” — risk increases with age, and the next polyp can develop after the test - “You don’t need to screen again” — repeat testing every 1–3 years is standard, depending on risk

What to do next: - Continue routine surveillance per your risk profile - Average risk, asymptomatic: repeat in 2–3 years - Family history or higher risk: repeat in 1–2 years - See a GP if you develop new symptoms regardless of the test result

A negative result is reassuring. It’s not a guarantee. Stay alert to symptoms.

A positive ColoAlert result

What it means: Markers were detected suggesting either current colorectal cancer or significant pre-cancerous polyps. It does NOT mean you have cancer — many positive results turn out to be polyps or, occasionally, false positives.

What to do next: colonoscopy is the standard recommended next step.

A colonoscopy lets a specialist look inside your colon, find any polyps or tumours, biopsy anything suspicious, and remove polyps in the same session. It remains the gold standard for definitive diagnosis.

In the UK you have two routes:

Private colonoscopy: - Cost: £1,500–£3,000 - Available within 1–2 weeks at most private hospitals - Day-case procedure under sedation - Results usually back within a week of the procedure

NHS colonoscopy: - Free - Wait times vary — a positive ColoAlert from a private clinic, accompanied by a referral letter, can sometimes accelerate an NHS referral - Your private clinician can write a letter to your NHS GP recommending urgent referral - The 2-week-wait pathway applies if symptoms are present alongside the positive result

A small number of people get a positive result and a clean colonoscopy. This can happen when polyps have already been removed elsewhere, in some early-stage findings outside the colon, or simply as a false positive. Your specialist will advise on follow-up screening intervals.

What the specific markers mean

ColoAlert reports more than just positive/negative. The specific markers detected can give clues about what’s been picked up.

Blood (haemoglobin) only positive: Suggests bleeding from somewhere in the lower GI tract. Could be cancer, polyps, haemorrhoids, inflammation, or other benign causes. A colonoscopy is needed to identify the source.

DNA markers only positive: Less common. The cancer or polyp may not be actively bleeding. Strong indication for colonoscopy.

Both blood and DNA markers positive: The strongest signal in the test. Colonoscopy is essential and should not be delayed.

Your clinical results report will give specifics. A clinician-led results consultation can talk through what each marker means in your individual context.

Common reasons for a positive result besides cancer

A positive ColoAlert can be triggered by:

• Pre-cancerous polyps (the test’s whole point — catching these before they become cancer)

• Benign polyps (some can shed markers)

• Haemorrhoids or fissures (cause bleeding that mimics cancer markers)

• Diverticular disease

• Inflammatory bowel disease (Crohn’s, ulcerative colitis)

• Recent gastrointestinal bleeding from other causes

• Rarely, false positives with no identifiable cause

Most positive ColoAlert results turn out to be polyps or benign causes — but the only way to know is to look inside.

An inconclusive or “borderline” result

Occasionally a ColoAlert result comes back inconclusive — markers at the threshold but not clearly positive. The lab may recommend repeating the test or proceeding to colonoscopy depending on your symptoms and risk.

This is uncommon, and a clinician should walk you through the specific recommendation. Don’t ignore an inconclusive result — repeat or investigate as advised.

What if my result is positive but I have no symptoms?

This is actually the point of screening. Most cancers and almost all pre-cancerous polyps cause no symptoms in their early stages. A screen-detected positive result in an asymptomatic person represents exactly the early detection you were hoping for.

Don’t be reassured by absence of symptoms. The test is finding what your body isn’t yet telling you about.

What if my result is negative but I have symptoms?

A negative result does not override symptoms. If you have:

• Persistent change in bowel habit (more than 3 weeks)

• Visible blood in stool

• Unexplained weight loss

• Persistent abdominal pain

• Unexplained iron-deficiency anaemia

• A lump in your abdomen

…you should see a GP regardless of the test result. About 15% of bowel cancers don’t shed detectable markers, and other conditions need investigating in their own right. ColoAlert is a screening tool, not a diagnostic one.

What about the original screening interval?

After a clear ColoAlert:

• Average risk, age 40–50: repeat every 2–3 years

• Average risk, age 50+: repeat every 2 years

• Family history (one first-degree relative with bowel cancer): repeat every 1–2 years

• Strong family history or known genetic syndrome: colonoscopy surveillance is usually preferred over stool testing

• Personal history of polyps: follow your specialist’s recommended surveillance interval

The right interval is personal. Discuss with a clinician who knows your history.

After a colonoscopy following positive ColoAlert

Possible outcomes and what they typically mean:

Normal colonoscopy: You can be reassured. Discuss future screening intervals with your specialist — usually return to ColoAlert in 3–5 years, sometimes longer.

Polyps found and removed: This is exactly the kind of result that screening saves lives over. Surveillance colonoscopy at intervals (1–5 years depending on polyp type) usually replaces stool testing for a few years.

Cancer found: Early-stage screen-detected colorectal cancer has very high survival rates — over 90% at 5 years for stage 1. You’ll be referred into a specialist colorectal cancer service for staging and treatment planning. Catching it through screening, rather than from symptoms, is the best possible scenario.

Inflammatory bowel disease found: Less common, but ColoAlert can occasionally pick this up. You’ll be referred to a gastroenterology service for ongoing care.

Frequently asked questions

How long do ColoAlert results take? Usually 10–15 working days from when the lab receives your sample.

Can I do another ColoAlert instead of a colonoscopy if I get a positive result? No. A positive result needs investigation, not retesting. The next step is to look inside the colon, not to take another stool sample.

Will my NHS GP help me get an NHS colonoscopy after a private positive result? Usually yes. With your consent, we can send a copy of your result to your NHS GP with a recommendation for urgent referral. NHS referral times for ColoAlert-positive results are improving as the test becomes more recognised.

What does ColoAlert cost compared to a colonoscopy? ColoAlert is around £350–£450. A private colonoscopy is £1,500–£3,000. Both have very different roles — ColoAlert is screening, colonoscopy is diagnostic and therapeutic.

Can I have ColoAlert if I’m on blood thinners or have haemorrhoids? Yes. The blood component will be more likely to be positive, but the DNA component is what makes ColoAlert distinct. A clinician will help interpret the result in your context.

Are private health insurers covering ColoAlert? Some policies cover it as a screening test with appropriate clinical indication. Coverage is improving but still patchy — check with your insurer.

Can ColoAlert pick up other cancers like stomach or pancreatic? No. ColoAlert is specific to colorectal cancer. Stomach, pancreatic, and other GI cancers need different investigations.

In summary

A negative ColoAlert is reassuring but not a guarantee. Continue routine surveillance and stay alert to symptoms.

A positive ColoAlert is not a cancer diagnosis. It means colonoscopy is needed — and most positives turn out to be polyps or benign causes. The point is to find these things early enough to act on.

Whichever result you get, a clinician-led discussion of what it means for your individual situation matters far more than the headline word “positive” or “negative.” Numbers on a screening test only have meaning in clinical context.

About the author

Dr Chun Tang (MBChB, MRCGP, MBA) is a GMC-registered private GP, co-founder of Northwest Health in Bamber Bridge, Preston, and Medical Director of Biox Medical Ltd — the UK distributor of ColoAlert®. He brought the test to the UK after losing his father to bowel cancer. His work has been featured in The Daily Telegraph, The Mirror, BBC and GB News.

Need to discuss a ColoAlert result?Book a private GP consultation for a clinician-led review and onward referral pathway if needed.