Mya Care Blogger 22 Jun 2023

A colonoscopy is a procedure utilized to examine the large intestine, which includes the colon, rectum, and anus. It is a form of endoscopy that uses a flexible tube with a lit camera introduced into your body as the instrument.

Endoscopes come in a variety of forms for use in various body parts. During a conventional colonoscopy, the colonoscope enters your colon through your rectum and anus. Along the way, it transfers images of the insides of your large intestine to a screen.

There are two types of colonoscopy: diagnostic and screening. A screening colonoscopy is a preventive medical check performed to detect and treat colorectal cancer early. On the other hand, a diagnostic colonoscopy is performed to investigate abnormal symptoms, test results, pre-existing conditions, or family history.

What Is A Virtual Colonoscopy?

A virtual colonoscopy is a new colonoscopy procedure that employs an X-ray to scan your colon and rectum for polyps (growths), ulcers (sores), and cancer. The process involves a visual examination of the colon, capturing images of the insides of your large intestine from outside your body. Computerized tomography (CT) colonography is another name for virtual colonoscopy.

During the CT scan, images of the large intestine are captured. After the scan, a computer combines these images to provide 2-D and 3-D internal visualizations of the large intestine. An MRI may be used instead of a CT scan in some circumstances.

A regular colonoscopy has been the gold standard screening test for conditions such as:

  • Rectal bleeding
  • Presence of blood in the stools
  • Pus or mucus in the feces
  • Abdominal pain without a known cause
  • Altered bowel patterns like persistent and unexplained diarrhea
  • Colorectal cancer

Virtual colonoscopy is one of the colonoscopy alternatives, apart from double-contrast barium enema, sigmoidoscopy, fecal immunochemical testing (FIT), and fecal occult blood test (FOBT).

Starting at age 45, colorectal cancer screening is advised for everyone, according to health professionals. However, a younger screening age may be necessary if you are at a higher risk for colorectal cancer. Colorectal cancer risk factors include:

  • History of colorectal cancer in the family.
  • Genetic diseases such as Lynch syndrome or familial adenomatous polyposis (FAP) increase your risk of developing colon polyps or colorectal cancer.
  • Inflammatory bowel diseases, such as ulcerative colitis and Crohn's disease.

Virtual colonoscopy is one method for screening for colorectal cancer. A traditional colonoscopy or a stool test are other tests that your doctor may recommend.

Virtual Colonoscopy Vs. Traditional Colonoscopy - How Are The Two Approaches Different?

Here are the key ways traditional colonoscopy differs from virtual colonoscopy:

Ability to remove polyps: During a conventional colonoscopy, your doctor can remove polyps; however, this is impossible during a virtual colonoscopy. If your doctor discovers polyps during a virtual colonoscopy, a traditional colonoscopy would be required as a follow-up to remove them.

Sedation: Anesthesia is required for a traditional colonoscopy, so you would be comfortable or sleeping throughout the operation. However, you would require time off from work and someone to drive you home after the procedure due to the sedation involved. Since there is no need for sedation or anesthesia during a virtual colonoscopy, you can return to your regular routine immediately after the procedure.

Test duration: A colonoscopy can last up to 90 minutes, although it may take longer if polyp removal is involved. The average time for a virtual colonoscopy is 15 minutes.

Equipment: A colonoscope, a camera mounted on a long, flexible tube, is used during a standard colonoscopy to view your colon. However, in a virtual colonoscopy, images from a CT scan are used and collected from outside your body.

Virtual Colonoscopy For Colorectal Cancer Screening - How Does It Compare With Other Alternatives?

Concerning colorectal cancer screening, a few commonly asked questions include, “Can a CT scan detect colon cancer?”, “Is a virtual colonoscopy as good as a regular colonoscopy?”, and “What is better, a virtual colonoscopy or a regular colonoscopy?”

Virtual colonoscopy is one of the tests utilized for colorectal cancer screening, apart from conventional colonoscopy, double-contrast barium enema, sigmoidoscopy, and stool tests such as fecal immunochemical testing (FIT), and fecal occult blood test (FOBT).

For a double-contrast enema, a metallic liquid (barium) is inserted into the colon via a tube. While it can easily find lesions in the colon, the procedure can be uncomfortable and embarrassing. Virtual colonoscopy, in contrast, is less invasive.

Sigmoidoscopy can be uncomfortable and cannot check the entire colon. The FIT test also does not check the entire colon and cannot diagnose cancer as a standalone screening method. FOBT requires multiple stool samples and is not 100% accurate in detecting blood in the stools.

According to studies, virtual colonoscopies can detect most biologically significant polyps and cancer with detection rates comparable to regular colonoscopies.

Benefits Of Virtual Colonoscopy

The advantages of virtual colonoscopy include:

  • Detailed, clear, 2D, and 3D images are observed during a virtual colonoscopy.
  • You recover more quickly since you are not sedated.
  • The procedure is less invasive and painless since it does not involve inserting a scope into the colon.
  • Compared to a colonoscopy, there is less chance of colon injury.
  • It is appropriate for those who cannot undergo anesthesia or a conventional colonoscopy. For instance, it is one of the recommended colonoscopy alternatives for elderly patients.
  • It takes photos of your entire colon, even if you have narrowed areas in your gut or bowel obstruction.

Risks And Side Effects Of Virtual Colonoscopy

X-rays are used in a virtual colonoscopy, which exposes you to very little radiation. Long-term exposure to large amounts of radiation doses raises the risk of developing cancer. However, the radiation exposure from a virtual colonoscopy is minimal. According to experts, the benefits of detecting colon cancer outweigh this risk.

Additionally, inflating your bowel with air has a slight risk of bowel perforation (tear in your bowel). Compared to a conventional colonoscopy, the risk of intestinal perforation is lower with a virtual colonoscopy.

Who should not get a Virtual Colonoscopy?

CT colonography is unsuitable for individuals who meet any of the below criteria.

  • If you are or think you could be pregnant
  • Personal or family history of colon cancer or colonic polyps
  • Chronic inflammatory bowel diseases such as Crohn's disease or ulcerative colitis
  • Recent colonoscopy involving biopsy or polypectomy, which carries an increased risk of perforation or worsening an undetected perforation
  • Intestinal obstruction
  • Toxic megacolon, a rare yet potentially fatal distension of the colon
  • History of acute diverticulitis

Additionally, the contrast medium may be unsafe for those with specific medical conditions and may interact with some drugs. Tell your provider the following before scheduling your virtual colonoscopy so that necessary recommendations can be factored in.

  • Prescription medications you use (dietary supplements included)
  • Whether you have any allergies or medical issues.

Who Performs A Virtual Colonoscopy?

Your virtual colonoscopy is done by a qualified X-ray technician who collects all the photos. The images are then examined by a radiologist, a medical professional specializing in medical imaging, looking for colon polyps, ulcers, or areas that might be malignant or precancerous.

What Is The Prep For A CT Colonography?

You will undergo a bowel preparation, or "prep," before your virtual colonoscopy. This procedure clears your colon of all stools for your doctor to examine your colon and rectum. You would prepare similarly for a virtual colonoscopy as you would for a standard colonoscopy. You typically complete your preparation the day before your virtual colonoscopy.

Your doctor will advise you on how to prepare for your virtual colonoscopy, which may include:

  • Enemas: These are drugs injected into the rectum to induce bowel movements.
  • Laxatives: Powders or liquids that cause frequent bowel movements.
  • Clear liquid diet: Consume only clear liquids the day before the treatment, such as water, apple juice, fat-free broth, and plain coffee or tea. You will receive a list of foods and beverages you can consume from your physician before your preparation.
  • Fasting: You must go a few hours without eating or drinking before treatment.
  • Drinking a contrast medium: By consuming a contrast medium, you can help your doctor see your colon more clearly.

A complete bowel preparation is required for an effective virtual colonoscopy. Plan to stay home and close to a restroom during your preparation because it will cause regular, watery diarrhea.

CT Colonography Procedure - How Is It Done?

A virtual colonoscopy typically involves the following steps:

While lying on a table, a short tube, about 2 inches long, is inserted into your rectum by the technician. This device gradually pumps air into your intestine, inflating it and making it easier to see the finer details.

The table will slide you slowly into the CT scanner, which resembles a short tunnel. The CT scanner commences capturing photographs of your colon.

While the CT scanner takes photos, it is important to lie perfectly still. Using an intercom system, the technician will converse with you while the process is underway. During the exam, they might ask you to hold your breath for a short time or switch positions.

Following the completion of your exam, the table glides you out of the scanner. The tube will then be removed from your rectum to complete the procedure.

What Happens After Virtual Colonoscopy?

Following your virtual colonoscopy, you can resume your regular activities and eat and drink as usual. A virtual colonoscopy typically has very little to no recovery time due to the lack of anesthesia.

Because of the air that was forced into your colon, you might experience some extra gas. This is typical; the gas could make you feel cramped or bloated. Usually, this is not a serious issue.

Interpreting Virtual Colonoscopy Results

It does not necessarily indicate that you have colorectal cancer if your doctor discovers an anomaly or a polyp during your virtual colonoscopy. However, you will require a second colonoscopy so that your doctor can remove the polyp or abnormalities.

After your virtual colonoscopy, your provider might perform a conventional colonoscopy to remove any abnormal findings. This can be useful if you have already finished your bowel preparation. Alternatively, you might have to postpone your colonoscopy.

Ask your doctor when you should have your next colorectal cancer screening if your test results are normal. For example, you might require a second virtual colonoscopy every five years if your risk of colorectal cancer is minimal.

When Should You Contact Your Doctor?

Call your doctor immediately if you experience any of the following symptoms after your virtual colonoscopy.

  • Blood in the stool or blood flow from the rectum
  • Fever
  • Dizziness
  • Severe abdominal pain


For many patients, a virtual colonoscopy is an effective alternative to a regular colonoscopy because of its lower risk of problems and quicker recovery. Discuss your options with your physician to determine which colorectal screening test is best for you.

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