Colonoscopy, Cologuard, or a Blood Test? How to Choose a Colon Cancer Screening Test — and What Insurance Covers
"A colonoscopy? Maybe next year." Most people put it off for years — because of the prep, the embarrassment, or fear of the bill.
That's a shame, because colorectal cancer is one of the few cancers you can do more than catch early. You can often prevent it. Most of these cancers grow slowly out of a polyp, and removing the polyp removes the problem.
Colonoscopy isn't your only option. But the options aren't equal, and which one you pick decides what you'll learn and what you'll pay.
Who should screen, and when
The U.S. Preventive Services Task Force (USPSTF, 2021) recommends:
Ages 45–49: start screening
Ages 50–75: screen everyone
Ages 76–85: decide with your clinician, based on your health and past results
Over 85: usually no longer needed
The American Cancer Society (ACS) also recommends starting at 45.
That's for people at average risk. If you've had colorectal cancer or polyps, have inflammatory bowel disease (Crohn's or ulcerative colitis), or a parent, sibling, or child had colorectal cancer, you'll likely start earlier and go straight to colonoscopy. Your clinician sets the schedule.
And if you have blood in your stool, a change in bowel habits that won't go away, anemia, or weight loss you can't explain, that isn't screening anymore. You need a diagnostic colonoscopy, not a home test.
Your options
Colonoscopy — every 10 years
A doctor examines your entire colon with a flexible camera and removes polyps on the spot. It's the only test that finds cancer and prevents it in the same visit. If everything looks normal, the next one is in 10 years.
The downsides: prep, sedation, a day off, and someone to drive you home. Serious complications are rare. The USPSTF estimates about 3 perforations and about 15 serious bleeds per 10,000 colonoscopies.
FIT (fecal immunochemical test) — every year
FIT looks for hidden blood in stool. You collect a small sample at home — no diet changes — and mail it in. It's the least expensive option.
The catch: you have to do it every year, and it misses most precancerous polyps. In the large BLUE-C study, FIT caught 67% of cancers and about 23% of advanced precancerous polyps.
Cologuard (stool DNA) — every 3 years
Cologuard looks for blood plus DNA from abnormal cells in stool. The current version, Cologuard Plus, was FDA-approved in 2024. In BLUE-C it caught 94% of cancers and 43% of advanced precancerous polyps — clearly better than FIT.
The trade-off is more false alarms: about 9 in 100 people with no cancer and no advanced polyps get a positive result.
The kit comes to your home, and you ship it back free. Official how-to videos are available in 15 languages, including Russian (link below).
A similar newer option, ColoSense (a multitarget stool RNA test), was added to the ACS recommendations in 2026.
Blood test (Shield) — every 3 years
Shield, from Guardant Health, became the first FDA-approved blood test for colorectal cancer screening in 2024. One blood draw, no stool sample.
In May 2026, the ACS added blood tests to its guidelines for the first time — but not as a preferred option. The ECLIPSE study shows why: Shield detected 83% of cancers but only 13% of advanced precancerous polyps. It can find cancer, but it rarely gives you the biggest benefit of screening, which is removing a polyp before it turns into cancer.
The ACS recommends it for people who decline both colonoscopy and stool tests. It's better than no screening. The USPSTF doesn't recommend blood tests yet.
CT colonography and sigmoidoscopy — every 5 years
CT colonography ("virtual colonoscopy") images the colon with a CT scanner. Same bowel prep, no sedation, but polyps can't be removed during the test. Flexible sigmoidoscopy examines only the lower part of the colon. Both are used less often in the U.S.
Side by side
Colonoscopy — How often: every 10 years; Finds cancer: best; polyps removed during the test; Finds advanced polyps: best; Prep: bowel prep, sedation
FIT — How often: every year; Finds cancer: 67%; Finds advanced polyps: about 23%; Prep: none
Cologuard Plus — How often: every 3 years; Finds cancer: 94%; Finds advanced polyps: 43%; Prep: none
Shield (blood) — How often: every 3 years; Finds cancer: 83%; Finds advanced polyps: 13%; Prep: none
FIT and Cologuard Plus figures are from the BLUE-C study; Shield figures are from ECLIPSE (both published in NEJM, 2024).
Any positive home test means a colonoscopy
A positive FIT, Cologuard, or blood test isn't a diagnosis. It's a signal, and the next step is a colonoscopy, ideally within a few months. If you already know you wouldn't get a colonoscopy no matter what the result said, a home test won't help you.
What insurance covers
Private insurance (ACA plans). Screening from 45 to 75 — colonoscopy, FIT, Cologuard, CT colonography, sigmoidoscopy — is covered with no copay or deductible when you use in-network providers. Removing a polyp during a screening colonoscopy shouldn't cost you anything either; federal guidance treats it as part of the screening. Since 2023, most private plans must also cover the follow-up colonoscopy after a positive stool test (FIT or Cologuard) without cost-sharing.
Medicare. A screening colonoscopy is free if your provider accepts assignment. FIT is covered yearly, and Cologuard and the Shield blood test every 3 years, for ages 45–85. A colonoscopy after a positive home test also counts as screening and is fully covered.
One catch: if a polyp is removed, you pay 15% of the doctor's Medicare-approved amount (coinsurance), plus possible facility coinsurance. By law, that drops to 10% in 2027 and 0% in 2030.
Medicaid coverage varies by state.
Where surprise bills come from
You have symptoms. Then the colonoscopy is billed as diagnostic, not screening, and cost-sharing can apply.
An out-of-network anesthesiologist or lab. Check that the anesthesiologist and the pathology lab are in-network, not just the gastroenterologist.
A blood test on private insurance. Shield isn't USPSTF-recommended yet, so a private plan may not cover it.
Surveillance after polyps. Some plans bill earlier repeat colonoscopies as diagnostic.
Before you book, call your insurer and ask: "Will this be billed as a screening colonoscopy? Will I owe anything if a polyp is removed?" Ask the clinic for the procedure codes so the insurer can give you a precise answer.
What happens during a colonoscopy
You lie on your side, an IV is placed, and an anesthesia provider gives sedation — usually propofol. Most people sleep through it and remember nothing. The doctor passes a flexible camera through the rectum, inflates the colon with air or carbon dioxide so the lining is visible, and removes any polyps with a small wire loop or forceps. The tissue goes to a lab.
The procedure itself takes 20–40 minutes; plan on 2–3 hours at the facility. Afterward you may feel bloated and gassy for a short while. The doctor usually tells you what they saw right away; lab results take 1–2 weeks.
You can't drive that day, and many facilities won't let you leave alone in a taxi or rideshare. Line up a ride in advance.
How to prepare
The prep matters more than anything else. If stool is left behind, the doctor can miss a polyp and you may need to repeat the whole thing. Follow your facility's instructions over anything you read online. In general:
A week before:
Tell the doctor what you take, especially blood thinners (Eliquis, Xarelto, warfarin, clopidogrel/Plavix), insulin or diabetes pills, iron, and GLP-1 medications such as semaglutide (Ozempic, Wegovy) or tirzepatide (Mounjaro, Zepbound). Don't stop a blood thinner on your own.
Iron is usually stopped several days ahead.
Pick up your prescription bowel prep.
2–3 days before: Many facilities ask you to skip seeds, nuts, popcorn, corn, and raw fruits and vegetables with skins.
The day before: A low-residue diet or clear liquids only — water, clear broth, apple juice, tea or coffee without milk, gelatin. Nothing red, purple, or dairy.
The prep itself is almost always split-dose: half the evening before, half the morning of the procedure, finishing 4–6 hours beforehand. Split dosing gives the cleanest colon.
You're ready when what comes out is clear yellow liquid, like tea, with no flecks.
A few things that help:
Chill the solution and drink it through a straw.
Suck on a hard candy or sip clear apple juice between glasses.
Keep soft toilet paper or flushable wipes and a zinc oxide cream nearby.
If you feel sick, pause for 30 minutes, then drink more slowly. If you're vomiting and can't finish, call the facility.
If you take a GLP-1 medication, 2024 multi-society guidance says most people can keep taking it, but you may be asked to follow a liquid diet for 24 hours before the procedure because these drugs slow stomach emptying.
Cologuard at home
Your clinician orders the kit, and it arrives by mail. You collect a sample in a container that fits on the toilet, take a small scraping with the included probe, add the preservative, and ship the box back free by UPS. Results take about two weeks.
Official how-to video in Russian (Exact Sciences, about 4 minutes): How to use Cologuard — Russian. Other languages and printed guides: cologuard.com/resources.
Cologuard isn't for you if you've had polyps or colorectal cancer, have inflammatory bowel disease, or have a strong family history. You need a colonoscopy instead.
Our recommendation
The best test is the one you'll actually do. If you're free to choose:
If you can handle the prep, choose colonoscopy. One procedure covers 10 years, and polyps come out on the spot.
If you can't, do Cologuard every 3 years or FIT every year. That's real screening, not a compromise — as long as you stay on schedule and get a colonoscopy if the result is positive.
Use the Shield blood test only if you'd refuse both colonoscopy and stool tests. It catches most cancers but very few polyps.
Not sure which test fits you, how to check your coverage, or what to do after a positive result? Book a visit with DobroMed Online.
What about Galleri and Cancerguard?
You may have heard about new blood tests that look for more than 50 cancers at once: Galleri from GRAIL, and Cancerguard from Exact Sciences, the company behind Cologuard. In short:
They are not colon cancer screening and don't replace colonoscopy or Cologuard. They often miss early cancers and don't look for polyps at all.
Neither is FDA-approved. FDA advisers voted in favor of Galleri on September 23, 2026, and a final decision is pending. Cancerguard is a lab-developed test; the company hasn't filed for FDA approval yet.
Insurance usually doesn't pay. Galleri costs $949 and Cancerguard $689. Both are HSA/FSA-eligible.
Do you need a referral? Both require a prescription, but not a referral from your own doctor. You can order online, and a telehealth clinician reviews your answers and writes the prescription.
Cancerguard: cancerguard.com/request. A Recuro Health clinician writes the order at no extra cost. For ages 50+, or 18–49 with a risk factor. Not for anyone with cancer in the past 3 years or during pregnancy. Not yet available in New York.
Galleri: galleri.com/get-started/patients. An independent telemedicine provider reviews the request. Recommended from age 50. Not for pregnancy, age 21 or younger, or active cancer treatment.
Does Cancerguard really pay for scans after a positive result? Yes, with conditions. Its Positive Result Support program reimburses up to $6,000 for imaging your insurance doesn't cover. You have to apply, approval isn't guaranteed, and it doesn't cover copays, deductibles, or coinsurance. Phone: 1-844-870-8870. Galleri has no comparable program.
Why Cancerguard offers it. The test doesn't say where a cancer signal comes from, so a positive result leads to contrast CT of the neck, chest, abdomen, and pelvis. It also has more false alarms: roughly 26 per 1,000 people without cancer, versus about 4 for Galleri.
We'll compare Galleri and Cancerguard in detail in a separate article.
Sources
USPSTF. Screening for Colorectal Cancer, 2021. https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/colorectal-cancer-screening
American Cancer Society colorectal cancer screening guideline update, CA Cancer J Clin, May 27, 2026 (summary: Medical Daily). https://www.medicaldaily.com/shield-blood-test-colorectal-cancer-acs-guidelines-2026-colonoscopy-476282
Imperiale TF et al. Next-generation multitarget stool DNA test (BLUE-C). NEJM, 2024. https://ascopost.com/issues/may-10-2024/cell-free-dna-blood-based-test-and-next-generation-multitarget-stool-dna-test-in-colorectal-cancer-screening/
Chung DC et al. A cell-free DNA blood-based test for colorectal cancer screening (ECLIPSE). NEJM, 2024. https://pubmed.ncbi.nlm.nih.gov/38477985/
American Cancer Society. Insurance coverage for colorectal cancer screening. https://www.cancer.org/cancer/types/colon-rectal-cancer/detection-diagnosis-staging/screening-coverage-laws.html
Medicare.gov. Colonoscopies (screening). https://www.medicare.gov/coverage/colonoscopies
Cologuard resources and multilingual videos. https://www.cologuard.com/resources
Cancerguard results and Positive Result Support. https://www.cancerguard.com/test-results
Cancerguard FAQ (price, reimbursement, FDA status). https://www.cancerguard.com/faq
Galleri pricing and payment. https://www.galleri.com/patient/the-galleri-test/cost
GRAIL. FDA Advisory Committee vote on Galleri, Sept 23, 2026. https://grail.com/press-releases/fda-advisory-committee-votes-in-favor-of-approval-of-grails-galleri-multi-cancer-early-detection-test/
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