CT Colonography (Virtual Colonoscopy) of the Colon/Rectum — Without IV Contrast, With Air Contrast Per Rectum
A CT scan that uses air inserted through the rectum to examine the colon for polyps and other abnormalities without injecting IV contrast.
["This imaging test uses rectal air and CT scans to look for colon polyps and disease without an injected dye."]
Key facts at a glance
- LOINC
- 79071-7
- Short code
- CT Colon+Rect WO contr IV+W air contr PR
- Synonyms
- CT Colon+Rect WO contr IV+W air contr PR
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ct
- CPT
- 86592
- 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?
CT colonography, also called virtual colonoscopy, creates detailed pictures of the inside of the colon using a CT scanner. Air is introduced through the rectum to expand the colon so the lining can be examined.
Why might I need this test?
It may be used to look for polyps, colorectal cancer, diverticular disease, narrowing, bleeding, or other colon problems. It may be considered when standard colonoscopy cannot be completed or is not appropriate.
How is the test performed?
A small tube is placed in the rectum, and air is pumped in to distend the colon. CT images are taken as you change positions. The air contrast is inserted through the rectum; no IV contrast dye is injected during this test.
How do I prepare for the test?
Follow the imaging center's instructions, which usually include a clear-liquid diet and laxatives or an enema to empty the bowel. Tell the staff about medicines, blood-thinning agents, mobility problems, or possible pregnancy before the appointment.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The scan may identify polyps, tumors, diverticula, narrowing, inflammation, or a possible source of bleeding. Suspicious or symptomatic findings may require a standard colonoscopy for direct viewing, removal, or biopsy. CT colonography can still miss small or flat lesions, so results should be interpreted together with symptoms and other screening history.
Short name
CT colonography without IV contrast
Frequently asked questions
Is CT colonography the same as a colonoscopy?
What does "air contrast" mean?
Why is bowel preparation important?
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