CT Colonography

CT Colonography or virtual colonoscopy is a quick, non-invasive procedure which evaluates the large intestine for cancer and growths called polyps. During the exam, a small tube is inserted a short distance into the rectum to allow for inflation with gas while CT images of the colon and rectum are taken.


CT Colonography Criteria

The criteria for a CT Colonography is the same as that of Optical Colonoscopy. Currently, CT Colonography is typically reserved for patients with a prior “incomplete” or “failed” Optical Colonoscopy to complete screening of the colon not visualized at Optical Colonoscopy due to current insurance coverage.

How to Prepare

Patients should expect to undergo a similar bowel preparation to that of Optical Colonoscopy. Your doctor may restrict you to clear fluids on the day before the CT and give you instructions on clearing your bowels. You will be instructed not to eat or drink anything for a few hours before your exam. This preparation is important for cleaning out the colon to allow for proper evaluation.


What to Expect

When you arrive for your appointment, a CT technologist will first perform a preliminary scan to ensure that the colon is prepped sufficiently to proceed with the exam. If there is too much stool remaining in the colon, you may be asked to undergo an additional day of bowel preparation to ensure a high quality diagnostic study can be performed.

After verifying that the bowel preparation is sufficient, the CT technologist will insert a very small, flexible tube a short distance into the rectum. From the tube, a small balloon will inflate the colon with CO2 gas, securing it within the rectum to prevent gas from leaking out. This expands the colon so that the radiologist can evaluate the colon in its entirety.

Next, the exam table will move you through the scanner. You will be asked to hold your breath for about 15 seconds or less before the technologist repositions you for a second pass through the scanner.

Infrequently, a third scan may be required with the technologist positioning you on your side to ensure the colon is adequately assessed. After the imaging portion is done, the rectal tube balloon will be deflated, the gas and rectal tube will be removed, and the procedure is finished.

The entire exam is usually completed within 15 minutes.


What Will I Experience During and After the Procedure?

The vast majority of patients who have a CT Colongraphy report a feeling of fullness when the colon is inflated during the exam, as if they need to pass gas. While slightly uncomfortable, significant pain is uncommon.


Insurance Coverage

When ordered as a screening exam most insurances do not cover CT Colonography. However, if you have an insurance that includes this study in their coverage, we will bill your insurance.

Please note: In some cases your provider may order this as a diagnostic exam in which case most insurances will cover it.

Where is CT Colonography Offered?

CT Colonography is offered at the following location:

More Information on this Exam

Colon cancer is the third most common cancer in men and women, and the third leading cause of cancer-related deaths in the country. In 2016, over 141,000 new cases of colon/rectal cancer were diagnosed and 52,286 reported deaths occurred from colon/rectal cancer in the US. Fortunately, colon cancer is one of several cancers that the general population can be screened for, allowing us to find and treat the cancer at an early stage when the cancer is most responsive to treatment.

The United States Preventative Task Force (USPSTF) is an entity tasked with creating screening recommendation guidelines for various cancers. Panels of experts review the medical literature and expert opinion from various fields of medicine to come up with the appropriateness and frequency of screening tests. Colon cancer has a Grade A recommendation (highest grade possible) for screening patients age 50-75. Screening options include various stool tests every 1-3 years, Optical Colonoscopy once every 10 years, Optical Sigmoidoscopy once every 5 years, and CT Colonography (Virtual Colonoscopy) once every 5 years.

CT Colonography is a safer, less invasive method than Optical Colonoscopy or Sigmoidoscopy. However, suspicious lesions/polyps detected on CT Colonography will typically require a follow up Optical Colonoscopy to biopsy and/or remove the lesion detected on CT Colonography.

CT Colonography obtains CT images of the entire abdomen and pelvis and therefore may discover “incidental findings” (abnormal findings outside of the colon) that may require further work-up such as ultrasound, contrast-enhanced CT, or MRI. Incidental findings are made in 40-70% of screening exams with 5-37% of these incidental findings requiring diagnostic follow-up (i.e. imaging follow-up) and approximately 3% of incidental findings requiring definitive treatment (including discovering cancers outside of the colon).

For more information, please visit: https://www.cdc.gov/cancer/colorectal/index.htm