Colonoscopy
A colonoscopy uses a flexible camera to examine the lining of the colon and rectum for polyps, inflammation, bleeding, or cancer.
["A colonoscopy can detect and help remove precancerous growths before they become cancer."]
Key facts at a glance
- LOINC
- 67221-2
- Short code
- Colonoscopy PhenX
- Synonyms
- Colonoscopy PhenX
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- phenx
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What is this test?
A colonoscopy is an examination of the large intestine using a thin, flexible tube with a camera. The scope is passed through the anus while your doctor looks for polyps, irritated tissue, bleeding, or other abnormalities. Small tissue samples may also be collected for laboratory examination.
Why might I need this test?
Colonoscopy may be recommended to screen for colorectal cancer, investigate blood in the stool, rectal bleeding, persistent abdominal symptoms, or unexplained changes in bowel habits. It may also be used to monitor certain people with previous polyps or inherited conditions that increase the risk of colorectal cancer.
How is the test performed?
Before the procedure, the bowel is cleaned with a prescribed bowel-preparation regimen. During the colonoscopy, the scope is gently moved through the colon so the entire lining can be examined. Polyps or suspicious areas may be removed, and tissue samples may be sent to a laboratory for further review.
How do I prepare for the test?
Follow the bowel-cleansing instructions exactly, because a poorly prepared colon can make the examination incomplete. Your care team will also provide instructions about food, fluids, and medicines. Tell the healthcare professional performing the procedure about kidney disease, swallowing problems, diabetes, blood thinners, or allergies before taking the preparation.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Findings may include polyps, inflammation, ulcers, bleeding, narrowing, or other changes in the bowel lining. Polyps are important because some types can develop into colorectal cancer, although many are benign and can be removed during the procedure. Biopsy results may be needed to distinguish normal tissue from inflammation, precancerous changes, or cancer.
Short name
Colonoscopy
Frequently asked questions
Does a colonoscopy hurt?
Will I be able to go home afterward?
What happens if a polyp is found?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy