Preventing Colon Cancer
There are several tests that are used to try and detect polyps. Several government agencies as well as the American Cancer Society recommend that patients undergo a test that allows the doctor to see the entire colon at age 50 and then every three to five years. Currently there are two accepted methods for seeing the entire colon; the Conventional Colonoscopy and the Barium Enema.
Other tests like the Flexible Sigmoidoscope or Rigid Sigmoidoscope, which can only see a small portion of the large bowel (colon), are considered inferior tests. Although the Barium Enema and Conventional Colonoscopy permit visualization of the entire colon, the sensitivity of Barium Enema is far from optimal and is uncomfortable both for patient and examiner. Conventional Colonoscopy is associated with increased risk and cost. Conventional Colonoscopy is unable to see the entire colon in 1 out of ten people. In addition, Conventional Colonoscopy may cause an injury of the colon (tear or perforation) in one of 1500 patients. Medication given into the vein (intravenous sedation) is usually required to make the exam bearable and, therefore, patients cannot resume normal activities immediately after the test.
The introduction of a safe, noninvasive, and effective method of detecting colorectal polyps and cancers has obvious appeal and has been the reason researchers at the Center for Virtual Colonoscopy at Boston Medical Center and other medical centers are pursuing evaluation of Virtual Colonoscopy.
Virtual Colonoscopy uses a standard computed tomography (CT) scan of the abdomen, which allows radiologists (special physicians with advanced training in x-ray imaging) to create pictures on the computer that look similar to those seen by Conventional Colonoscopy. Patients need a cleansing preparation of their bowel prior to the test. The day of the test, they come to the radiology department for a CT scan. The actual Virtual Colonoscopy procedure will begin by having a small flexible rubber tube placed in the rectum, so that air or carbon dioxide can be introduced. A CAT scan is then performed while patients lie comfortably on their back and then on their stomach. The total time required for the study is approximately 15 minutes. Because sedation is not required, patients are free to leave the CT suite immediately without the need for observation or recovery. Patients can resume normal activities immediately after the procedure and can eat, work or drive without a delay. Doctors (radiologists) analyze the CT data to detect colon polyps or cancers.
When air is introduced in the colon some patients experience minimal temporary abdominal cramping or "gas pains." An intravenous injection of a widely used medicine to relax the bowel can also be given to help reduce gas pains, but this is usually not necessary.
Virtual Colonoscopy Insurance Coverage
Virtual Colonoscopy is not currently reimbursed by most insurance companies. As a result, patients will have to assume the cost of the procedure themselves – A charge of 750 to 1200$ depending on the centers performing the test. Medicare patients: some centers require patients with medicare to sign a waiver informing them that at the moment, because virtual colonoscopy is a non-covered service, they accept accept responsibility for the payment in full. Their Medicare carrier may be initially billed and upon denial of the claim, which can be expected, patients are billed directly.
Non Medicare patients: Patients on private or HMO insurance plans are usually expected to pay the full charge prior to getting the test.
Virtual Colonoscopy is a promising new method for detecting colorectal polyps and cancers. Air is insufflated into a cleansed colon, and high resolution, thinly-collimated spiral CT slices are acquired. The two dimensional slices, as well as the post-processed "fly-through" virtual colonoscopic images, are examined for polyps and tumors. Research performed at Boston University and elsewhere has shown that Virtual Colonoscopy is better able to see polyps than Barium Enema and is nearly as accurate as Conventional Colonoscopy. In addition, most patients report that the Virtual Colonoscopy technique is more comfortable than either Barium Enema or Conventional Colonoscopy
Our data at Boston Medical Center also suggests that Virtual Colonoscopy is likely to be superior to Double Contrast Barium Enema, which has a reported sensitivity in the range of 65% to 75% for detecting polyps > 7 mm.
Virtual Colonoscopy is minimally invasive, and does not carry the low but real (1 in 1500) risk of perforation associated with Conventional Colonoscopy. It is well tolerated by patients and does not require sedation. It is capable of evaluating the colon upstream from obstructing lesions that prevent passage of an endoscope. Virtual Colonoscopy is significantly less expensive than Conventional Colonoscopy.
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