When Should Your Patient Have a Colonoscopy?
For average-risk adults, begin colonoscopy screening at age 50 and continue every 10 years until age 75. 1, 2, 3
Average-Risk Screening Algorithm
Starting Age
- Begin screening at age 50 years for asymptomatic adults without personal or family history of colorectal cancer, adenomatous polyps, or inflammatory bowel disease 1, 2, 3
- Consider starting at age 45 years only in African Americans, where limited evidence supports earlier screening 4
- The American College of Physicians recommends against routine screening between ages 45-49 in average-risk adults due to uncertainty around benefits versus harms in this age group 3
Screening Interval
- Colonoscopy every 10 years is the recommended interval for average-risk individuals with normal findings 1, 2, 4
- Alternative first-tier option: Annual fecal immunochemical test (FIT) if colonoscopy is declined 4
Stopping Age
- Stop screening at age 75 years in adults who are up to date with prior screening and have negative colonoscopy results 1, 2, 3
- For ages 76-85, individualize decisions based on comorbidities, life expectancy, and prior screening history—those never previously screened are most likely to benefit 2
- Do not screen adults older than 85 years 1
- Stop screening when life expectancy is less than 10 years 3
High-Risk Screening: Family History
One First-Degree Relative with CRC or Advanced Adenoma
If diagnosed before age 60:
- Begin colonoscopy at age 40 OR 10 years before the youngest affected relative's diagnosis, whichever comes earlier 1, 5, 4
- Repeat every 5 years 1, 5, 4
If diagnosed at age 60 or older:
- The National Comprehensive Cancer Network recommends starting at age 40 with colonoscopy every 5-10 years, though some guidelines suggest average-risk screening starting at age 40 5, 4
- Risk is approximately 1.8-1.9 times higher than someone with no family history 5
Two or More First-Degree Relatives with CRC (Any Age)
- Begin colonoscopy at age 40 OR 10 years before the youngest affected relative's diagnosis 1, 4
- Repeat every 5 years 1
High-Risk Screening: Other Conditions
Hereditary Nonpolyposis Colorectal Cancer (HNPCC/Lynch Syndrome)
- Begin colonoscopy at age 20-25 years OR 10 years before the youngest affected family member 1
- Repeat every 1-2 years, then annually after age 40 1
- Genetic counseling and testing are essential 1
Familial Adenomatous Polyposis (FAP)
- Begin flexible sigmoidoscopy annually starting at puberty (age 10-12 years) 1
- Genetic counseling and testing are mandatory 1
- Consider timing of colectomy if polyposis develops 1
Inflammatory Bowel Disease
- Begin surveillance colonoscopy 8 years after onset of pancolitis OR 12-15 years after onset of left-sided colitis 1
- Repeat every 1-2 years looking for dysplasia 1
Post-Polypectomy Surveillance
Low-Risk Adenomas (1-2 small tubular adenomas <1 cm with low-grade dysplasia)
- Repeat colonoscopy in 5-10 years 6
High-Risk Adenomas (3-10 adenomas, any ≥1 cm, villous features, or high-grade dysplasia)
- Repeat colonoscopy in 3 years 1, 6
- Evidence shows 85% increased risk of advanced adenoma at follow-up with 3 adenomas versus 1 adenoma 6
After Curative Resection of Colorectal Cancer
- Complete colonoscopy within 1 year after resection if not done preoperatively 1
- If normal, repeat at 3 years, then every 5 years thereafter 1
Critical Pitfalls to Avoid
Inadequate Bowel Preparation
- When bowel preparation is inadequate for screening, repeat colonoscopy as soon as possible if the indication was alarm symptoms or positive FIT 1
- For average-risk screening with inadequate preparation, repeat within 1 year 1
- If only the right colon was inadequately prepared but left colon/rectum well-visualized, consider offering alternative screening (FIT, flexible sigmoidoscopy) rather than repeat colonoscopy 1
Family History Verification
- Always verify the exact diagnosis and age of affected relatives through medical records when possible, as family-reported information is frequently inaccurate 5
Quality Indicators
- Ensure colonoscopy is performed by an endoscopist with adenoma detection rate ≥25% in men 5
- Require cecal intubation rate >90% and withdrawal time ≥6 minutes 5, 6
- Studies show colonoscopists with withdrawal times ≥6 minutes detect nearly 3 times more neoplasia 6
Common Mistake: Waiting Too Long with Family History
- Do not wait until age 50 to begin screening in patients with any first-degree relative with colorectal cancer—ideally start at age 40 5
Follow-Up After Positive Stool Tests
- All positive FIT or stool-based tests must be followed by colonoscopy to complete the screening process 2