What is Virtual Colonoscopy? Purpose, Procedure & Results

Virtual colonoscopy is a non-invasive imaging test that uses CT scans to create detailed pictures of your colon and rectum. Think of it as getting a thorough look inside your intestines without needing a flexible tube inserted through your rectum like in traditional colonoscopy.

This advanced screening method can detect polyps, tumors, and other abnormalities in your large intestine. Many people find it more comfortable than conventional colonoscopy since you don't need sedation and recovery time is minimal.

What is virtual colonoscopy?

Virtual colonoscopy, also called CT colonography, uses computed tomography scanning to examine your colon from the inside. The procedure creates hundreds of cross-sectional images that computers assemble into a three-dimensional view of your entire colon.

During the scan, a small, flexible tube is gently inserted just inside your rectum to inflate your colon with air or carbon dioxide. This helps open up the colon walls so the scanner can capture clear images of any growths or abnormalities.

The entire imaging process typically takes about 10-15 minutes. You'll lie on a table that moves through the CT scanner, first on your back, then on your stomach to get complete views from different angles.

Why is virtual colonoscopy done?

Virtual colonoscopy serves as an effective screening tool for colorectal cancer, particularly for people who cannot undergo traditional colonoscopy. It's recommended for adults starting at age 45-50, depending on your risk factors and family history.

Your doctor might suggest this test if you have symptoms like unexplained abdominal pain, changes in bowel habits, or blood in your stool. It's also useful for people who have had incomplete traditional colonoscopies due to technical difficulties.

Some patients choose virtual colonoscopy because they prefer avoiding sedation or have medical conditions that make traditional colonoscopy riskier. However, it's important to understand that if polyps are found, you'll likely need a follow-up traditional colonoscopy to remove them.

What is the procedure for virtual colonoscopy?

The virtual colonoscopy procedure begins with bowel preparation, similar to traditional colonoscopy. You'll need to follow a clear liquid diet and take prescribed laxatives to empty your colon completely before the test.

On the day of your procedure, you'll change into a hospital gown and lie on the CT table. A technologist will gently insert a small, flexible tube about 2 inches into your rectum to deliver air or carbon dioxide into your colon.

The scanning process involves these steps:

1. You'll lie on your back while the table moves through the CT scanner
2. The technologist will ask you to hold your breath for short periods during scanning
3. You'll then turn onto your stomach for additional images
4. The entire scanning takes about 10-15 minutes
5. After scanning, the tube is removed and you can resume normal activities

Most people experience mild cramping from the air inflation, but this discomfort typically resolves quickly after the procedure. You won't need sedation, so you can drive yourself home and return to work the same day.

How to prepare for your virtual colonoscopy?

Preparation for virtual colonoscopy requires clearing your colon of all waste material, just like traditional colonoscopy. Your doctor will provide specific instructions, but preparation typically begins 1-2 days before your test.

The bowel preparation process usually includes:

• Following a clear liquid diet for 24 hours before the test
• Taking prescribed laxatives or bowel prep solutions
• Drinking plenty of clear fluids to stay hydrated
• Avoiding solid foods, dairy products, and colored liquids
• Taking prescribed contrast material to help highlight any remaining stool

Some doctors prescribe special contrast agents that you'll drink over several days before the test. These help distinguish between leftover stool and actual polyps or abnormalities during the scan.

You should continue taking your regular medications unless your doctor advises otherwise. Since you won't receive sedation, you don't need to arrange transportation, but having someone accompany you can provide emotional support.

How to read your virtual colonoscopy results?

Virtual colonoscopy results are typically available within 24-48 hours after your procedure. A radiologist will carefully examine all the images and provide a detailed report to your doctor, who will then discuss the findings with you.

Normal results mean no polyps, tumors, or other abnormalities were detected in your colon. This suggests your risk of colorectal cancer is currently low, and you can follow standard screening intervals recommended by your doctor.

Abnormal results might show:

• Small polyps (less than 6mm) that may be monitored with repeat screening
• Medium polyps (6-9mm) that might require closer surveillance
• Large polyps (10mm or larger) that typically need removal via traditional colonoscopy
• Suspicious masses or growths that require further evaluation
• Inflammation or other non-cancerous conditions affecting your colon

If significant abnormalities are found, your doctor will recommend follow-up testing, usually traditional colonoscopy with the ability to remove polyps or take tissue samples. This doesn't necessarily mean you have cancer, but it ensures any concerning findings are properly addressed.

What are the advantages of virtual colonoscopy?

Virtual colonoscopy offers several benefits that make it appealing for many patients. The procedure doesn't require sedation, so you avoid the grogginess and recovery time associated with traditional colonoscopy.

Key advantages include:

• No sedation needed, allowing immediate return to normal activities
• Lower risk of complications like bleeding or bowel perforation
• More comfortable for many patients
• Ability to detect abnormalities outside the colon
• Suitable for patients who cannot undergo traditional colonoscopy

The procedure also provides images of organs around your colon, potentially detecting other health issues like kidney stones or abdominal aneurysms. Many patients find the experience less intimidating than traditional colonoscopy.

What are the limitations of virtual colonoscopy?

While virtual colonoscopy is an excellent screening tool, it has some limitations you should understand. The test cannot remove polyps or take tissue samples, so abnormal findings require follow-up traditional colonoscopy.

Other limitations include:

• May miss very small polyps or flat lesions
• Cannot remove polyps during the procedure
• Requires the same bowel preparation as traditional colonoscopy
• Exposes you to a small amount of radiation
• May produce false positive results requiring additional testing

The test might also detect incidental findings in other organs, which could lead to additional worry and testing even if they're not clinically significant. Your doctor will help you weigh these considerations against the benefits.

When should I see a doctor about virtual colonoscopy?

You should discuss virtual colonoscopy with your doctor if you're due for colorectal cancer screening, typically starting at age 45-50. This conversation becomes especially important if you have risk factors like family history of colorectal cancer or inflammatory bowel disease.

Consider scheduling a consultation if you're experiencing symptoms like persistent changes in bowel habits, unexplained abdominal pain, or blood in your stool. Your doctor can determine whether virtual colonoscopy is appropriate for your situation.

You might also want to discuss this option if you've been avoiding traditional colonoscopy due to anxiety or medical concerns. Virtual colonoscopy could provide a more comfortable alternative while still offering effective screening.

What are the risks of virtual colonoscopy?

Virtual colonoscopy is generally very safe, with significantly fewer risks than traditional colonoscopy. The most common side effects are mild and temporary, including cramping from air inflation and minor discomfort during the procedure.

Rare but possible risks include:

• Bowel perforation from air inflation (extremely rare, less than 1 in 10,000 cases)
• Allergic reaction to contrast material (if used)
• Radiation exposure from CT scanning
• Dehydration from bowel preparation
• Electrolyte imbalances from prep medications

The radiation exposure from virtual colonoscopy is relatively low, comparable to the natural background radiation you'd receive over 2-3 years. Most experts agree that the cancer detection benefits outweigh this minimal radiation risk.

If you experience severe abdominal pain, fever, or signs of dehydration after the procedure, contact your doctor immediately. These symptoms could indicate complications that need prompt medical attention.