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Computed tomographic (CT) colonography, diagnostic, including image postprocessing; without contrast material

CPT4 code

Name of the Procedure:

Computed Tomographic (CT) Colonography, Diagnostic, Without Contrast Material
Common Name: Virtual Colonoscopy


Computed tomographic (CT) colonography, also known as virtual colonoscopy, is a non-invasive imaging procedure used to examine the colon and rectum for signs of abnormalities, including polyps and cancerous growths. Unlike traditional colonoscopy, it does not require the insertion of a long tube into the colon.


The procedure is primarily used to screen for colorectal cancer and polyps, as well as to investigate unexplained abdominal symptoms like pain or bleeding. The goal is to detect any abnormalities early when they are most treatable.


  • Screening for colorectal cancer in individuals aged 50 and over, or earlier based on family history or other risk factors.
  • Persistent abdominal pain or discomfort.
  • Unexplained changes in bowel habits.
  • Blood in the stool.
  • Patients unable or unwilling to undergo traditional colonoscopy.


  • The patient will need to follow a special diet and take a bowel-cleansing agent to empty the colon prior to the procedure.
  • Fasting is usually required for a specified period, typically from the night before the procedure.
  • Any ongoing medications may need adjustment as advised by a healthcare provider.

Procedure Description

  1. The patient changes into a gown and lies on the CT scanning table.
  2. A small, flexible tube is inserted into the rectum to gently inflate the colon with air for better imaging.
  3. The CT scanner, a doughnut-shaped machine, takes multiple cross-sectional images of the abdomen and pelvis.
  4. The images are then processed using specialized software to create a detailed, 3D view of the colon.


The entire procedure typically takes about 30 minutes.


The procedure is usually performed in a radiology department within a hospital or an outpatient imaging center.


The procedure is conducted by a radiologist with the assistance of radiology technicians.

Risks and Complications

  • Mild abdominal discomfort or bloating due to air inflation.
  • Rare risk of bowel perforation.
  • Exposure to low doses of radiation.
  • False positives or negatives that may require further testing.


  • Non-invasive and generally more comfortable than traditional colonoscopy.
  • No need for sedation, allowing patients to resume normal activities almost immediately.
  • Effective at detecting larger polyps and cancers.


  • Patients can go home the same day and usually return to their normal diet and activities immediately.
  • Mild bloating or gas may occur but typically resolves quickly.


  • Traditional optical colonoscopy: more invasive, requires sedation but allows direct biopsy/removal of polyps.
  • Flexible sigmoidoscopy: examines only the lower part of the colon.
  • Fecal occult blood test (FOBT) or fecal immunochemical test (FIT): non-invasive tests detecting blood in the stool.

Patient Experience

  • The patient might feel mild discomfort or pressure from the air inflation.
  • Minimal pain, and usually no sedation is required.
  • A sensation of fullness and passing gas post-procedure as the body expels the introduced air.

Medical Policies and Guidelines for Computed tomographic (CT) colonography, diagnostic, including image postprocessing; without contrast material

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