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CT Colonography for Colorectal Cancer Screening, Without IV Contrast, With Air, Prone

Published: August 9, 2026Updated: August 16, 2026

A CT-based colon exam that uses air to examine the colon for polyps and colorectal cancer without intravenous contrast.

Quick summary

["This screening test uses CT images to look for colon polyps and cancer without IV contrast."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
79069-1
Short code
CT Colon+Rec Screen WO contr IV+W air PR
Synonyms
CT Colon+Rec Screen WO contr IV+W air 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, uses computed tomography to create pictures of the lining of the colon. Air may be used to expand the colon so polyps and other abnormalities are easier to see.

Why might I need this test?

It may be used to screen for colorectal cancer or investigate symptoms such as blood in the stool, unexplained rectal bleeding, or changes in bowel habits. Some people who cannot complete a standard colonoscopy may be offered this test.

How is the test performed?

After the colon is cleaned, a small tube is placed in the rectum to introduce air. The scanner takes pictures while you change positions, including a prone position. No intravenous contrast is used for this version of the test.

How do I prepare for the test?

You will need to empty your colon with laxatives and follow the food and drink instructions provided by the imaging center. Tell the care team about medications, allergies, mobility limitations, or any prior reaction to sedatives before the appointment.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

The test may identify polyps, colorectal cancer, or other abnormalities in the colon. If a suspicious finding is seen, a traditional colonoscopy may still be needed for closer examination, biopsy, or polyp removal. A limited examination can occur when the colon is not fully cleaned or when bowel-gas and motion artifacts obscure the images.

Short name

CT Colonography (Virtual Colonoscopy)

Frequently asked questions

Is CT colonography the same as a standard colonoscopy?
No. CT colonography is an imaging test that does not require a scope to pass through the colon. If it finds something suspicious, a standard colonoscopy may be needed to examine or treat it.
Does this test use IV contrast?
No. This version is performed without intravenous contrast. Air is used to expand the colon during the scan.
Can this test miss small or flat polyps?
It can. CT colonography is very useful for finding many polyps and cancers, but some small or flat lesions may be difficult to detect. Proper bowel preparation and image review are important.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

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