What is a virtual colonoscopy?
Virtual colonoscopy is a patient-friendly, safe and comfortable procedure for colon screening. It does not use drugs, IV contrast agents or injections. The screening is completed in 30 to 40 minutes, is read by a radiologist and the results are reported to the patient’s gastroenterologist or primary care physician. Because there is no anesthesia, patients do not need to be driven to the exam and are immediately free to resume everyday activities.
How does it work?
Virtual colonoscopy uses Computed Tomography (CT) scanning to obtain an interior view of the colon that can ordinarily only be seen with an endoscope inserted into the rectum. During the procedure, a small rubber tube is inserted into the rectum so that the colon can be filled with air. Some patients experience minimal temporary cramping or discomfort. Pictures are then taken of the patient’s abdomen and pelvis using a CT scan while lying face up and face down. The total time required for the study is approximately 30 to 40 minutes.
This minimally invasive test provides three-dimensional images that can depict many polyps and other lesions as clearly as when they are directly seen by optical colonoscopy. Polyps are benign growths that arise from the inner lining of the intestine. Some polyps may grow and turn into cancers. The goal of the screening is to find these growths in their early stage, so that they can be removed before cancer develops. With virtual colonoscopy, 100 percent of the colon surface can be seen. Recent studies have shown the screening to be comparable to conventional colonoscopy for finding polyps larger than one centimeter. The risk of cancer in smaller polyps is almost less than a percent.
What are the current methods used to detect polyps?
Conventional colonoscopies and barium enemas are often used.
What are the reasons for using virtual colonoscopy?
Reasons can include:
- an incomplete or failed traditional colonoscopy including redundancy, obstructing lesions and multiple diverticula
- preoperative assessment of the colon proximal to an occlusive cancer
- screening for polyps - an alternative for patients who have clinical factors that increase the risk of complications from colonoscopy.
Poor pre-colonoscopy preparation is not an indication for a virtual colonoscopy.
What are the benefits of virtual colonoscopy?
It evaluates the colon after an incomplete traditional colonoscopy examination or near an obstructing cancer. Virtual colonoscopy is well tolerated. Sedation and pain-relievers are not needed, which eliminates the recovery period. Patients are free to resume usual activities immediately after the exam.
Virtual colonoscopy is an alternative substitute for a colonoscopy for patients who, for a number of reasons, cannot or should not have a conventional colonoscopy.
Virtual colonoscopy is a minimally invasive procedure. It markedly lowers the risk of perforating the colon that may occur with conventional coloscopy.
What are the limitations of virtual colonoscopy?
Virtual colonoscopy is strictly a diagnostic procedure. If any significant polyps are found, they will have to be removed by conventional colonoscopy. Virtual colonoscopy is not yet approved for colon cancer screening in asymptomatic individuals nor is it widely approved for diagnosis of colon symptoms unless there has been a prior incomplete or failed colonoscopy. Typically it is not for chronic constipation.
Virtual colonoscopy is a low dose CT not tailored to the evaluation of the non-colonic structures and organs. Evaluation of other abdominal structures needs to be referred to CT with oral and intravenous contrast.
Is virtual colonoscopy covered by my insurance?
Most insurance companies cover a virtual volonscopy after the patient has had an incomplete or failed colonoscopy. Screening virtual colonoscopy is not covered at this time.
How do I prepare for a virtual colonoscopy?
Patients are given a bowel preparation kit, which contains laxatives for cleaning out the bowel and oral contrast for identifying residual stool. Patient is on a clear liquid diet 24 hours prior to the screen.
When and how often do I need to have a test to screen for polyps?
Patients over 50 years old should be tested every five to seven years with barium enema, conventional colonoscopy or virtual colonoscopy.
What will happen after the exam?
After the exam, the technologist will process your images using a computer. A Radiologist will evaluate the images and dictate a report, which will be available to your physician.
How will I learn the results?
You will get the results of the exam from your doctor.
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