The short answer: An adenoma detection rate (ADR) is the share of a doctor's colonoscopies that find at least one precancerous polyp called an adenoma. The 2024 ACG/ASGE quality indicators set a minimum ADR of 35% (40% for men, 30% for women). Most practices track it, but you usually have to ask.
What is an adenoma detection rate?
An adenoma is a type of polyp that can turn into colorectal cancer over time. Finding and removing adenomas is how colonoscopy prevents cancer. The ADR measures how often a given doctor finds them.
The math is simple. Take all the patients a doctor scoped in a period. Count the ones who had at least one adenoma confirmed by the lab. Divide. If 40 of 100 patients had an adenoma, the ADR is 40%.
The 2024 ACG/ASGE quality indicators call ADR "the most clinically relevant and best validated quality indicator in colonoscopy." The definition changed in 2024. It now counts patients 45 and older having screening, surveillance, or diagnostic colonoscopy. It leaves out people whose colonoscopy follows a positive stool test or CT colonography, people with polyposis syndromes or inflammatory bowel disease, and exams done only to treat a known growth.
That change matters when you compare numbers. Older ADR figures often counted only first-time screening exams in people 50 and older. The 2024 paper notes that adding surveillance exams can raise a doctor's ADR by a significant amount.
What ADR should your doctor have?
The target has risen over time as doctors got better at finding polyps. Per the 2024 quality indicators paper:
- 2015 target: at least 25% overall (30% in men, 20% in women).
- 2024 target: at least 35% overall (40% in men, 30% in women).
The task force calls 35% a minimum, not a goal. It says doctors below 35% should take steps to improve. It also urges all colonoscopists to aim well above 35%, because cancer risk keeps falling as ADR rises. The same paper reports that the mean screening ADR in US gastroenterology practices had risen to 38% by 2018, based on a large national registry.
So a doctor who quotes an ADR of 25% is meeting an old standard, not the current one. A doctor in the 40s or 50s is doing well.
Why does ADR matter for cancer risk?
ADR is tied to the risk of interval cancer. That is a colorectal cancer found after a colonoscopy that should have caught it. Three large studies show the link.
- Poland, 2010. A New England Journal of Medicine study followed 45,026 people screened by 186 endoscopists. Patients of doctors with an ADR under 20% had interval cancer hazard ratios of about 11 to 12.5, compared with patients of doctors at 20% or higher.
- Kaiser Permanente, 2014. A second NEJM study looked at 314,872 colonoscopies by 136 gastroenterologists. ADRs ranged from 7.4% to 52.5%. Patients of doctors in the top fifth had about half the interval cancer risk of the bottom fifth (hazard ratio 0.52). Their risk of a fatal interval cancer was lower too (hazard ratio 0.38). Each 1% rise in ADR was linked to a 3% drop in cancer risk.
- Poland, 2017. A follow-up study in Gastroenterology tracked 294 endoscopists who got yearly feedback. Doctors whose ADR went up gave their patients a lower risk of interval cancer (hazard ratio 0.63) and of cancer death (hazard ratio 0.50).
The last study is the hopeful one. ADR is not fixed. Doctors who measure it and get feedback tend to improve.
Our guide on how often a colonoscopy misses polyps or cancer covers miss rates and post-colonoscopy cancer in more depth.
How do you find your doctor's ADR?
Most practices do not post ADR on a website. You usually have to ask. These steps work best when you take them before your procedure is booked.
- Call the office. Ask the scheduler or nurse whether the practice tracks ADR for each doctor. Many will pass the question to the doctor or the quality team.
- Ask at your consult. If you see the gastroenterologist before the procedure, ask directly. A doctor who tracks ADR can usually answer in seconds.
- Ask the endoscopy center. Hospital and surgery-center endoscopy units often track quality for every doctor who works there.
- Ask about a registry. Many practices send their data to GIQuIC, a quality registry run by the ACG and ASGE. ASGE reports that Medicare approved GIQuIC as a qualified clinical data registry for 2026, its 13th year in a row. A practice that reports to it measures ADR as a matter of routine.
Ask the question in a neutral way. "What is your adenoma detection rate?" is a normal question in 2026. A good doctor will not take offense.
What questions should you ask your gastroenterologist?
ADR is the main number, but it is not the only one. This checklist uses the targets in the 2024 ACG/ASGE quality indicators and the 2025 US Multi-Society Task Force bowel prep recommendations.
- "What is your adenoma detection rate?" A good answer: 35% or higher overall. Higher is better.
- "How often do you reach the cecum?" The cecum is the start of the colon, the far end of the exam. A good answer: at least 95% of exams, with photos to prove it. If the scope does not get there, see our guide on what happens after an incomplete colonoscopy.
- "What is your average withdrawal time?" This is the time spent looking at the lining while pulling the scope back out. A good answer: at least 8 minutes on average in normal exams. The 2006 standard was 6 minutes.
- "How often is the prep good enough?" A good answer: adequate prep in at least 90% of exams. The 2025 task force recommends tracking this for each doctor and each unit.
- "Do you use a split-dose prep?" A good answer: yes. The 2025 task force recommends split-dose prep, with half taken the evening before and half the day of the exam.
- "What is your serrated lesion detection rate?" This one is newer. A good answer: at least 6%. Do not worry if a doctor does not track it yet.
Your own prep is the part you control. A poor prep hides polyps, even from a doctor with a high ADR. Our complete colonoscopy prep guide walks through it step by step.
What can ADR not tell you?
ADR is a rate across hundreds of patients. It says nothing about your own result. A clear colonoscopy from a doctor with a 45% ADR is good news. It does not mean the doctor missed something.
ADR also depends on the patients a doctor sees. Men and older people have more adenomas, which is why the targets differ by sex. A doctor who sees many younger patients may have a slightly lower ADR for that reason alone.
Some doctors are slow to share numbers simply because their practice does not compute them. In that case, ask whether the endoscopy unit tracks quality, and how. If you have symptoms such as rectal bleeding, do not delay care while you shop for a doctor. You can review warning signs on symptom.md.
The bottom line
ADR is the best single measure of how well a doctor finds precancerous polyps. The current minimum is 35%, and higher is better. Ask for it, along with cecal intubation rate, withdrawal time, and prep quality, before you book. Then do your own prep well.
Last updated: October 2026. This article is for informational purposes only and does not constitute medical advice. Talk with your doctor about the colonoscopy plan that is right for you.