Bowel polyps

Understanding bowel polyps

What polyps are

A polyp is an overgrowth of the cells lining the bowel, forming a small lump that projects into the bowel cavity. Some sit on a stalk like a mushroom; others are flat and sessile, which makes them harder to spot and is one reason bowel preparation quality matters so much.

Polyps are common, particularly with increasing age, and most people who have them have no idea, because they almost never cause symptoms.

Understanding bowel polyps

The types that matter

Not all polyps carry the same significance, and the laboratory report after removal tells us which type you had.

Hyperplastic polyps are very common, usually small, and generally carry little or no cancer risk. Adenomas are the type that matters, because they are the recognised precursor to most bowel cancers. Sessile serrated lesions are a flatter type now known to carry meaningful risk and to be easy to miss.

Risk within the adenoma group rises with size, with number, and with certain features seen under the microscope.

Understanding bowel polyps

How polyps become cancer

The transformation from a benign adenoma to cancer is a gradual accumulation of genetic changes, typically taking a decade or more. This is called the adenoma-carcinoma sequence.

That long timeline is the entire foundation of bowel cancer screening. It gives us a wide window in which to find and remove a polyp before it has become anything, which is why colonoscopy prevents the disease rather than merely detecting it.

Understanding bowel polyps

Symptoms

Most polyps cause no symptoms whatsoever, which is precisely why waiting for symptoms is a poor strategy.

Larger polyps can occasionally cause visible bleeding, a change in bowel habit, or slow blood loss that shows up as iron-deficiency anaemia. But by the time a polyp is large enough to announce itself, it has usually been there a long time.

Understanding bowel polyps

Removal during colonoscopy

Polyps are removed during the same colonoscopy that finds them, a procedure called polypectomy. Small ones are taken with biopsy forceps or a cold snare; larger ones with a wire snare, sometimes after lifting them from the wall with an injection.

You feel nothing, because the bowel lining has no pain nerves of the kind your skin has. The removed tissue goes to the laboratory, and that report determines what happens next.

Bleeding after polypectomy is uncommon but possible, which is why we give clear post-procedure instructions before you leave.

Understanding bowel polyps

Surveillance afterwards

Once you have had adenomas removed, you are in a higher-risk group and need repeat colonoscopy at an interval decided by what was found.

In broad terms, one or two small low-risk adenomas mean a longer interval, often several years. Multiple polyps, large polyps, or polyps with higher-risk features under the microscope mean a shorter interval. If a large polyp had to be removed in pieces, an earlier check confirms the site is clear.

Keeping to that follow-up date is the whole value of having had the polyps removed in the first place.