Colonoscopy Screening: What to Expect, and Why Age 45 Is the New Starting Point

Colon cancer is one of the few common cancers that screening can actually help prevent, not just catch early — because the exam used to screen for it can also remove the precancerous growths (polyps) that would otherwise eventually turn into cancer. That's a meaningful part of why screening guidelines matter.

Why 45, Not 50

For years, average-risk screening started at 50. The U.S. Preventive Services Task Force updated that recommendation to age 45 after colorectal cancer rates among younger adults began rising. If you have a family history of colorectal cancer or polyps, inflammatory bowel disease, or certain genetic syndromes, your doctor may recommend starting even earlier — that's a conversation worth having directly rather than assuming the general guideline applies to you.

What a Screening Colonoscopy Involves

The day before: A prep process clears the colon so it can be examined clearly. This is usually the part people dread most, though prep regimens have improved significantly in palatability and volume over the years.

The day of: You'll receive sedation, so most people don't remember the procedure itself and don't feel discomfort during it. A thin, flexible camera examines the full length of the colon. If polyps are found, they're typically removed during the same procedure and sent for pathology.

After: Because of the sedation, you'll need someone to drive you home. Most people resume normal activity the next day.

What the Results Mean

• No polyps found: Depending on your risk factors, your next screening may be recommended in 10 years.
• Polyps removed: Follow-up timing depends on the number, size, and type of polyps — often 3 to 5 years, sometimes sooner.
• A finding that needs further evaluation: Your doctor will explain next steps, which may include additional imaging or a referral.

The Bottom Line

The procedure that feels like the biggest hurdle — the prep — is temporary. The payoff is a test that can prevent cancer, not just detect it. If you're 45 or older and haven't been screened, or if you have symptoms or a family history that might mean starting earlier, that's worth a conversation with your doctor.