A colonoscopy is a procedure that allows a gastroenterologist to examine the colon and rectum. It can help screen for colorectal cancer, find colon polyps, and evaluate symptoms such as rectal bleeding, bowel changes, diarrhea, anemia, or abdominal discomfort.
Medically Reviewed by Dr. Bharat Pothuri, MD, FACG | Updated 03-24-2026
A colonoscopy is a procedure that uses a thin, flexible tube with a camera to look inside the colon and rectum. It helps doctors check the lining of the colon for polyps, inflammation, bleeding, abnormal tissue, and signs of colorectal cancer.
A colonoscopy may be recommended as a routine screening test or as part of an evaluation for ongoing digestive symptoms.
A colonoscopy helps your GI doctor see the inside of your colon directly. If polyps or abnormal tissue are found, your doctor may remove or sample them during the procedure when appropriate.
A colonoscopy may be done to screen for colorectal cancer, evaluate digestive symptoms, or monitor known colon conditions.
Screening can help find colon polyps or cancer before symptoms appear.
Some patients need screening earlier or more often based on family history.
Colonoscopy can help identify possible bleeding sources in the colon or rectum.
Ongoing diarrhea, constipation, or new bowel pattern changes may need evaluation.
A colonoscopy may help check for hidden bleeding or other colon-related causes.
Patients with prior polyps may need repeat colonoscopy based on results and risk.
A colonoscopy gives your doctor a detailed view of the colon lining and can help identify several digestive health concerns.
Polyps are growths in the colon lining. Some types may become cancerous over time if not removed.
Colonoscopy can help detect colorectal cancer and is commonly used as a screening test.
It may show inflammation related to conditions such as ulcerative colitis or Crohn’s disease.
The procedure may help locate causes of visible or hidden bleeding in the lower digestive tract.
Colonoscopy can show small pouches in the colon wall and other structural findings.
If needed, tissue samples may be taken and sent for lab review to guide the next step.
Your doctor may recommend colonoscopy based on age, symptoms, family history, previous polyps, abnormal stool testing, or other risk factors.
Many adults need colorectal cancer screening even when they feel well.
Prior colon polyps may require future monitoring based on pathology and risk.
Family history can change when screening should begin and how often it is repeated.
Bleeding, ongoing bowel changes, anemia, or unexplained weight loss may need evaluation.
A positive stool-based screening test may lead to colonoscopy for direct evaluation.
Some patients with inflammatory bowel disease may need colon monitoring over time.
A colonoscopy can provide important information about colon health and may help prevent future problems by finding certain changes early.
A colonoscopy is commonly performed and is generally considered safe when done by trained specialists. As with any medical procedure, there can be risks, including bleeding, reaction to sedation, or rarely, injury to the colon wall.
Your doctor will review your medical history, medications, and risk factors before the procedure.
Talk to a gastroenterologist if you are due for colorectal cancer screening or if you have rectal bleeding, blood in the stool, persistent bowel habit changes, unexplained anemia, unexplained weight loss with digestive symptoms, or new abdominal pain with bowel changes.
Use these next-step pages when you are ready to understand preparation, scheduling, or related digestive conditions.
Learn about preparation, procedure day, sedation, recovery, and results.
Review appointment, location, insurance, and scheduling details.
Learn when bowel pattern changes may need evaluation.
Colonoscopy preparation usually involves diet changes, a bowel-cleaning medicine, medication review, and transportation planning. This overview page should explain why prep matters without replacing the detailed instructions your care team gives before the procedure.
Watch this overview in the bottom half of the page, then follow the written instructions from your GastroDoxs care team for your exact prep timing, medication guidance, arrival time, and transportation plan.
| Want procedure-day details? | Review the full guide for bowel prep, sedation, procedure-day expectations, recovery, and how results are discussed. Read what to expect during colonoscopy. |
| Ready to discuss screening? | If you are due for screening or have symptoms that may need evaluation, use the scheduling page to understand appointment options. See colonoscopy scheduling options. |
A colonoscopy is used to examine the colon and rectum. It may help screen for colorectal cancer, detect colon polyps, evaluate bleeding, and understand ongoing bowel symptoms.
No. Many adults need colonoscopy for routine colorectal cancer screening even if they do not have symptoms. It may also be recommended earlier if you have risk factors or concerning symptoms.
Yes. A colonoscopy can help identify colon polyps. In many cases, polyps may be removed during the procedure and sent for lab review.
You should ask a doctor about colonoscopy if you are due for colorectal cancer screening, have a family history of colon cancer, had previous polyps, or have symptoms such as rectal bleeding or ongoing bowel changes.
Yes. Colonoscopy can be used for screening and diagnosis. It may help doctors evaluate symptoms, detect inflammation, identify bleeding sources, and guide the next step in care.
A screening colonoscopy is usually done to look for polyps or colorectal cancer before symptoms appear. A diagnostic colonoscopy is done to evaluate symptoms or abnormal test results.
Colonoscopy can help prevent some colorectal cancers by finding and removing certain precancerous polyps before they have a chance to become cancer.