Written and medically reviewed by: Assoc. Prof. Cengiz Dibekoğlu, MD, General SurgeryLast updated:
Colonoscopy
Why it is done, preparation, procedure, aftercare
Colonoscopy is not only looking — polyps can be removed in the same session.
Colonoscopy uses a flexible camera to inspect the colon lining. It serves screening (catching polyps early), diagnosis (bleeding, stool change, anemia), and therapy (polypectomy, biopsy, stent, decompression, bleeding control) — often combined in one visit. Bowel prep quality determines whether small polyps are missed.
Educational schematic. Some structures may be simplified or emphasized for clarity; not an exact anatomical depiction.
© Cengiz Dibekoğlu — illustrative; not for unauthorized use
Figure summary
Hero figure: colonoscope, screening vs diagnostic vs therapeutic roles.
Screening
Preventive polyp and cancer detection.
Diagnostic
Symptoms and positive FIT work-up.
Therapeutic
Polypectomy, stent, decompression.
Prep
Bowel cleaning defines quality.
What to know
Why colonoscopy?
Screening by age and risk, diagnostic evaluation for bleeding or anemia, and therapeutic polyp removal, stenting, or decompression when findings appear.
- Key note inside
Diagnostic vs therapeutic
In brief: Even a ‘look only’ visit often becomes therapeutic if a polyp is found.Diagnostic exams look and sample; therapeutic sessions remove polyps, place stents, decompress obstruction, dilate strictures, or control bleeding in the same sitting.
- Key note inside
When is it requested?
For average-risk adults without symptoms, current U.S. screening guidelines begin at age 45; national programs may differ. Family history, inflammatory bowel disease, prior adenomas, and Lynch/FAP change timing. Alarm symptoms warrant diagnostic colonoscopy regardless of age.
Alternatives
FIT, stool DNA, or CT colonography screen — but positive tests still need colonoscopy; CT cannot remove polyps.
Polyp pathway
Adenomatous polyps can progress to cancer. Removed polyps are reviewed by pathology; surveillance intervals depend on polyp number, size, histology, completeness of resection, and bowel-prep quality — follow current guideline tables rather than a single fixed year for every patient. See the Colon Screening and Polyps chapter for detail.
What happens next
Diet, bowel prep, medications
- 1
Preparation
Diet, bowel prep, medications
Read this chapter - 2
Procedure
Pain, sedation, duration
Read this chapter - 3
Aftercare
Results and repeat timing
Read this chapter - 4
Colon Screening and Polyps
Polyp pathway and surveillance intervals
Read this chapter - 5
Colon Cancer
When cancer is found
Read this chapter
Patient education videos
From Dr. Dibekoğlu’s official YouTube channel.
Are colon polyps dangerous?
Common misconceptions about colon cancer
Colon cancer warning signs — do not ignore
Are large-bowel polyps dangerous?
Evidence
Scientific sources
Show sources · 3ACG / ASGE / U.S. Multi-Society Task Force guidance for colonoscopy preparation, sedation, polyp surveillance, and selected therapeutic stenting or decompression.
Evidence
Scientific sources
- 1. ACG clinical guidelines — GI disease and colorectal cancer screeningAmerican College of Gastroenterology (ACG) · Living guidelinesOpen source →
- 2. ASGE guideline library — endoscopy, polypectomy, and achalasiaAmerican Society for Gastrointestinal Endoscopy (ASGE) · Guideline libraryOpen source →
- 3. Recommendations for colorectal cancer screening and post-polypectomy surveillanceU.S. Multi-Society Task Force on Colorectal Cancer (AGA / ACG / ASGE) · Current guidanceOpen source →
Last reviewed: 21 August 2026. Links go to publisher pages.
Appointment / info
Bring your prep instructions, medication list, and a companion for sedation days.
This page is for education. It is not medical advice and does not replace a visit with your physician.
Medical editor: Assoc. Prof. Cengiz Dibekoğlu, MD · English patient-education hub.