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CT Colonography (CT Colon and Rectum Screening) with Air Contrast, Prone

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

CT colonography uses a CT scan and air to examine the colon and rectum for polyps and other abnormalities.

Quick summary

["This imaging test can help detect colon polyps and other colon abnormalities without an endoscope."]

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

Key facts at a glance

LOINC
79101-2
Short code
CT Colon+Rect Screening W Air contr PR
Synonyms
CT Colon+Rect Screening 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, uses a CT scanner and air to create detailed pictures of the colon and rectum. The prone position may be used to obtain images from different angles.

Why might I need this test?

This test may be used to screen for colorectal cancer or investigate symptoms such as unexplained rectal bleeding, persistent diarrhea, or changes in bowel habits. It can also provide an alternative to colonoscopy when appropriate.

How is the test performed?

A healthcare professional places a small tube into the rectum and inflates the colon with air. You may also be asked to drink an oral contrast agent, and the scanner takes images while you change positions, including lying on your stomach.

How do I prepare for the test?

Your colon must be thoroughly cleaned, usually with a bowel-cleansing preparation and specific dietary instructions. Tell the imaging center if you have kidney problems, diabetes, a history of contrast reactions, or are pregnant or may be pregnant.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CT colonography

Frequently asked questions

Is CT colonography the same as a standard colonoscopy?
No. CT colonography uses imaging and air rather than a long camera scope. If a polyp or another important finding is found, a standard colonoscopy may still be needed.
Does CT colonography use radiation?
Yes. Like other CT scans, it uses a small amount of ionizing radiation, but the procedure itself does not use radiation.
Will I need a bowel cleansing before the test?
Yes. A clean colon is necessary so that stool does not obscure the images. Follow the exact preparation instructions provided by your clinician or imaging center.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

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