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CT Colon and Rectum With and Without IV Contrast and Air Contrast, Preparation

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

A CT scan of the colon and rectum performed before and after IV contrast, with air used to expand the bowel for clearer images.

Quick summary

["This test uses CT imaging and bowel preparation to help identify polyps, cancer, and other colon or rectal abnormalities."]

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

Key facts at a glance

LOINC
82688-3
Short code
CT Colon+Rect WO+W contr IV+Air contr PR
Synonyms
CT Colon+Rect WO+W contr IV+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?

This is a CT scan of the large intestine, including the colon and rectum. Images may be taken before and after IV contrast, and air may be introduced into the bowel to help create clearer images of its inner lining.

Why might I need this test?

The test may be used to investigate blood in the stool, a change in bowel habits, unexplained abdominal symptoms, or polyps. It can also help detect colorectal cancer or evaluate inflammatory and other conditions affecting the colon or rectum.

How is the test performed?

You lie on a CT scanner table while X-ray images are taken around your body. IV contrast may be given through a vein, and air or another gas may be placed in the colon. The procedure usually takes a relatively short time, and a technician or radiologist guides the process.

How do I prepare for the test?

Bowel cleansing is usually required, so follow the facility's instructions about laxatives, enemas, food, and liquids. Tell the imaging team if you are allergic to iodinated contrast, have kidney disease, are pregnant or may be pregnant, or have bowel symptoms such as significant narrowing or blockage.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CT Colon/Rectum With and Without IV and Air Contrast

Frequently asked questions

Is this the same as a routine abdominal CT?
No. This study focuses on the inner lining of the colon and rectum and may use specially prepared bowel, air, and IV contrast to improve visualization.
Why must I complete a bowel preparation?
Cleaning out the bowel helps the scanner see the colon's inner surface and improves the ability to identify small polyps or other abnormalities.
Will I need sedation or experience significant discomfort?
Most people do not need sedation. Some may feel pressure from the air in the bowel, and an IV contrast injection may cause a brief warm sensation, but the imaging team can explain what to expect.
  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