Haemorrhoids are extremely common. So when someone gets a raised bowel test result and knows they have piles, the explanation seems obvious and the relief is immediate.
It is also, on the evidence, usually wrong. And it is the mistake most likely to cause harm.
What the studies found
The assumption that haemorrhoids drive false positive FIT results has been tested directly, more than once.
A Dutch study looked at patients undergoing colonoscopy and asked how often haemorrhoids alone explained a positive FIT. It found that only 4.1% of false positive results could be attributed to haemorrhoids as the sole abnormality. When haemorrhoids were the only finding, 6.7% had a positive FIT, compared with 4.9% in people with no abnormality at all. That difference was not statistically significant.
A 2023 study of nearly 10,000 patients found haemorrhoids did not meaningfully affect test performance. Sensitivity was 24.9% in people without haemorrhoids and 22.8% in people with them.
The evidence is not entirely one-directional. A Korean study did find an independent association with false positives. But the weight of the evidence points the same way: haemorrhoids are an infrequent explanation for a raised result.
Why this makes physiological sense
FIT detects breakdown products of haemoglobin in a stool sample, rather than fresh blood sitting on the surface.
Bleeding from haemorrhoids typically appears on the paper, or in the bowl, or streaked on the outside of the stool. It is not usually mixed through the sample the way bleeding from higher in the colon is.
So the kind of bleeding people can see, and attribute to piles, is not necessarily the kind of bleeding the test measures.
The mistake
Here is the part that matters more than any statistic.
Haemorrhoids are so common that a great many people have both haemorrhoids and something else. Finding piles does not mean nothing else is there. Explaining away a raised result on the basis of a condition that is present in a large proportion of the adult population is not reasoning, it is coincidence.
Clinical guidance is blunt on this: do not dismiss a positive FIT as “just haemorrhoids.” Colorectal neoplasia may coexist. This is described as the most dangerous error to make with the test.
The same guidance notes there is no rationale for adjusting for other conditions or medications when using FIT. The test does not need excuses made for it.
What a raised result actually deserves
Investigation on its own terms.
That does not mean panic. Most raised results do not turn out to be cancer, and that is worth holding onto. But “most raised results are not cancer” is a reason to be investigated calmly, not a reason to skip being investigated.
If you have a raised result and haemorrhoids, you have a raised result. The piles are a separate fact about you.
If this has already happened to you
If you have previously been told, or told yourself, that a raised result was down to piles, and you never had further investigation, it is worth raising again. Not because something is necessarily wrong, but because that particular reassurance does not hold up well, and it is a straightforward thing to resolve.
References
- Oort FA, et al. Haemorrhoids detected at colonoscopy: an infrequent cause of false-positive faecal immunochemical test results. Gastrointestinal Endoscopy 2012;76(1):136 to 143.
- Comparative performance of stool-based tests in patients with and without haemorrhoids, 2023 cohort study of ~10,000 patients.
- US Multi-Society Task Force on Colorectal Cancer. Recommendations on faecal immunochemical testing to screen for colorectal neoplasia: consensus statement.
Figures are drawn from the sources above. Framing and commentary are the author’s own. Last reviewed August 2026.