Gallbladder Polyps: What the Size Means, When They Are Watched and When the Gallbladder Comes Out

Gallbladder polyps are small growths or lumps on the inner lining of the gallbladder, usually found by chance on an ultrasound scan; most are harmless cholesterol deposits, and whether anything needs doing depends mainly on the polyp’s size and a short list of risk factors. A polyp of 10 mm or more is usually a reason to remove the gallbladder, a polyp of 5 mm or less in someone without risk factors usually needs nothing at all, and the sizes in between are watched with repeat scans¹.

I never had a polyp myself; my scan showed stones and nothing else. But the word turns up in messages to this site more than almost anything except “gas pain”, usually from someone who went for a scan about something else entirely and came home with a report that used the word “lesion”. I wanted to set out plainly what the guideline actually says, because the gap between the report and the follow-up appointment is a frightening place to sit. Every figure below has been checked by a consultant general surgeon.

What a gallbladder polyp is, and what it usually turns out to be

Most things called gallbladder polyps on a scan are pseudopolyps, small deposits of cholesterol or harmless thickening of the wall, which carry no cancer risk.

On an ultrasound, a polyp shows as a small bump projecting from the gallbladder wall into the space inside, and unlike a stone it does not move when you change position and does not cast an acoustic shadow. The European guideline groups these findings into pseudopolyps and true polyps. Pseudopolyps are most often cholesterol polyps, with focal adenomyomatosis and inflammatory polyps making up the rest; true polyps are mostly benign adenomas, and only rarely cancers. In the series reviewed for the 2017 guideline, about 70% of suspected polyps turned out to be pseudopolyps².

They are common. That guideline put the prevalence on abdominal ultrasound at between 0.3 and 9.5%², and a 2026 study described them as found incidentally on imaging in about 5% of the general population, adding that most are asymptomatic and only a very small percentage are malignant³. If you have just been told you have one, you are in large company.

Polyps and stones are different things, though they often turn up together. Stones are loose, form in the bile and are what cause most gallbladder attacks; gallstones explained covers how they form. A polyp is attached to the wall. The scan that finds one is usually an ordinary abdominal ultrasound, described in how gallstones are diagnosed.

Why size matters most

Size is the main thing guiding the decision because larger polyps are more likely to be true polyps, and true polyps carry a small chance of becoming cancerous.

The 2017 guideline explained the logic plainly: when a gallbladder is removed for a polyp of 10 mm or larger, the lesion is more likely to be malignant, and if it is not, it is more likely to be an adenoma with malignant potential². Smaller lesions are more often pseudopolyps. Ultrasound cannot reliably tell the two apart, so size stands in as the best practical guide, and the 2022 update recommends ordinary abdominal ultrasound as the main test, with contrast enhanced or endoscopic ultrasound reserved for difficult cases in centres with the expertise¹.

The guideline’s cut points are, in summary:

• 10 mm or more: removing the gallbladder is recommended, if you are fit for and accept surgery.
• 6 to 9 mm with one or more risk factors: removal is recommended, on the same condition.
• 6 to 9 mm with no risk factors, or 5 mm or less with risk factors: ultrasound follow-up at 6 months, 1 year and 2 years, stopping after 2 years if it has not grown.
• 5 mm or less with no risk factors: no follow-up needed¹.

The last line is worth dwelling on because it is newer than many people’s information. The 2017 version advised scans at 1, 3 and 5 years even for these tiny polyps². The 2022 update dropped that, and a 2026 real world study found that poor adherence to the guideline was leading to a lot of unneeded scans and some unneeded operations³.

The risk factors that change the advice

Four risk factors move a medium sized polyp toward surgery: age over 60, primary sclerosing cholangitis, Asian ethnicity, and a sessile (flat, broad based) polyp, including focal wall thickening over 4 mm.

Each has its reason. Gallbladder cancer is more common with age, and the 2022 update set the threshold at over 60 (the 2017 version used over 50)¹. Primary sclerosing cholangitis, a long term liver condition affecting the bile ducts, is associated with a higher chance that a gallbladder polyp is malignant. Gallbladder cancer is more common in some Asian populations, and the 2017 guideline cited a large study in which people of Indian ethnicity with polyps had a higher rate of gallbladder cancer². And a polyp that sits flat on a broad base, rather than on a stalk, was found to be an independent risk factor in several studies, which is why focal wall thickening is treated the same way.

Note what is not on the list. A single polyp is not treated as more worrying than several, and having gallstones as well was not judged strong enough evidence to count as a risk factor on its own, though many people with both will have symptoms that lead to surgery anyway².

What follow-up scans look like, and when a polyp has grown

Follow-up is a repeat abdominal ultrasound; reaching 10 mm means surgery is advised, and growth of 2 mm or more within the 2 year window prompts a closer look.

The 2022 guideline says that if a polyp grows to 10 mm during follow-up, removing the gallbladder is advised. If it grows by 2 mm or more within the 2 year period, the current size and your risk factors should be weighed together, sometimes in a multidisciplinary meeting, to decide whether to keep monitoring or operate. If it disappears from the scan, monitoring can stop¹. The 2 mm figure was chosen deliberately: a 1 mm change could simply reflect differences in scanning, while 2 mm is more likely to be real growth².

Most polyps do not grow. In the 2026 real world study, only about a quarter of polyps increased in size over an average follow-up of around two and a half years, and no malignant polyps were found among the 30 people who had their gallbladder removed³.

Do polyps cause symptoms?

Small polyps are unlikely to cause pain on their own, but if you have gallbladder type symptoms and no other cause is found, removing the gallbladder may be suggested.

The 2017 guideline was direct that small polyps themselves are unlikely to explain a person’s symptoms². Gallbladder attacks are usually caused by stones; gallbladder attack symptoms describes what one feels like. Even so, the 2022 guideline suggests removing the gallbladder for someone with a polyp and symptoms that could come from the gallbladder, if no other cause is found, with honest counselling about the chance that symptoms persist afterwards¹. That caveat matters: an operation can remove a gallbladder perfectly and still not touch pain that was coming from somewhere else, which is the subject of what gallbladder removal won’t fix.

If surgery is recommended

The operation for a polyp is the same keyhole cholecystectomy used for gallstones, and the removed gallbladder is examined under a microscope afterwards.

Removing the gallbladder for a polyp is usually a planned laparoscopic operation through three or four small cuts, often as a day case or with one overnight stay, with most people back to normal activities in about 1 to 2 weeks⁴. The details are in keyhole gallbladder surgery. As with stones, the gallbladder is not essential: the liver keeps making bile, which flows straight into the gut instead of being stored, and most people digest normally without it⁵.

What a polyp operation adds is the answer to the question the scan could not settle. The laboratory report on the removed gallbladder says what the polyp actually was, and for most people that answer is a cholesterol polyp or a benign adenoma.

Questions worth asking at your appointment

A reader who wrote to me after her first scan said the most useful thing she did was bring a written list, because the word “polyp” emptied her head the moment she sat down. These are the questions that match the guideline:

1. How big is the polyp, in millimetres, and is it one or several?
2. Does it look sessile (flat) or on a stalk?
3. Do I have any of the risk factors, and do any of my other conditions change the advice?
4. Does the guideline you are following recommend surgery, follow-up scans, or nothing?
5. If follow-up, when is each scan, and who will chase it if the appointment does not arrive?
6. Do I have gallstones as well, and could they explain any symptoms I have had?

Whether a polyp needs anything, and what suits you if it does, is a decision for a surgeon who has seen your scan and knows your health. What this page can do is make sure you go in knowing what the numbers on the report mean.