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Johns Hopkins Medical Imaging

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Virtual Colonoscopy

Virtual Colonoscopy Q&A

Karen Horton, M.D., professor and Chair of Radiology, discusses what is involved in the procedure, how to prepare and the benefits of virtual colonoscopy over conventional colonoscopy.

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Virtual colonoscopy is a special X-ray examination of the colon using low dose computed tomography (CT). It is a less invasive procedure than a conventional colonoscopy. Virtual colonoscopy look for small polyps or other growths inside your colon that may turn into colon cancer.

The American Cancer Society advises that most men and women begin screening for colon cancer at age 50. If you have a family history of colon cancer or are at high risk for other reasons, you may need to have screening even earlier. Virtual colonoscopy every five years is one of several screening choices.

How do I prepare for a virtual colonoscopy?

Before having a colonoscopy, you will need to have a bowel prep. A bowel prep helps you empty your colon so that the CT images will be clear. The prep kit will be mailed to you.

PRECAUTIONS: If you are pregnant or think you may be pregnant, please check with your doctor before scheduling the exam. Other options will be discussed with you and your doctor.

CLOTHING: You will be asked to change into a patient gown. A gown will be provided for you. Please remove all piercings and leave all jewelry and valuables at home.

EAT/DRINK: Specific instructions will be provided based on the examination you are scheduled for.

ALLERGIES: Notify the radiologist or technologist if you are allergic or sensitive to medications, contrast dyes or iodine.

What happens during a virtual colonoscopy?

Virtual colonoscopy are performed on selected CT scanners at John Hopkins Outpatient Center and Johns Hopkins Imaging sites. The schedulers will indicate the locations when you make your appointment. The scan takes only about 10 to 15 minutes. This is what happens during the test:

  1. The thin tube will be placed into your rectum. This is used to inflate your colon with air. You may feel a slight fullness.
  2. A radiologist will put you face up on a table that slides into the CT scanner.
  3. The radiologist will leave the room. The CT scanner will be operated from a separate control room. You will be able to hear and talk with the staff.
  4. The table will move into and through the scanner. You may hear some whirring and clicking noises.
  5. You may be asked to hold your breath at times.
  6. The scan may need to be repeated while you lie face down.
  7. Once the exam is complete the tube will be removed and the staff will give you further instructions.

What happens after a virtual colonoscopy?

In most cases, you should be able to return home without help. You can go back to your normal diet and activities. You will likely not need medicines or special instructions. Talk with your healthcare provider and the radiology staff if you have any questions.