What is CT Virtual Colonoscopy
CT Virtual Colonoscopy is a CT scan done in a special way that allows a radiologist (specialized physician trained in x-ray imaging) to look at the large bowel (colon) to detect polyps and cancers. Polyps are small growths in the colon. They include benign lesions, some of which may become cancerous if not removed. CT Virtual Colonoscopy is a technique that uses a CT scanner and computer virtual reality software to look inside the body without having to use sedation and without having to insert a long tube (Conventional Colonoscopy) into the colon or without having to fill the colon with liquid barium (Barium Enema). Additionally, the CT scan images allow a radiologist to see other areas in the abdomen that are not visualized by the other tests. In this manner, a potentially life threatening problem like cancer may be detected early, and possibly treated. At The University of Chicago, we have been doing research on virtual colonoscopy since 1996. We believe that CT Virtual Colonoscopy is safer, more comfortable, less expensive and faster than conventional colonoscopy. We know that it’s not as accurate a test as conventional colonoscopy, but data now show that it is a very good screening test for colon cancer.
Why is it Important
Colorectal cancer (CRC) is a leading cause of cancer-related death in the United States. In 2007 an estimated 112,340 new cases of colon cancer will be diagnosed in the United States, and 52,180 patients are expected to die of the disease. Colorectal cancer is the third most common cancer in men and women (and second most common when combining data for men and women). It is the most common cause of cancer deaths in non-smokers.
Research suggests that the incidence is declining due to increased screening and polyp removal, which prevents the progression of polyps into invasive cancers. Colon cancer can be prevented if polyps are discovered and removed early. Tumors, masses of abnormal cells, take years to develop. Initially, a cell from the colon starts to multiply abnormally and forms a benign (non-cancerous) polyp, which can remain harmless for a long time before becoming an aggressive cancer. Polyps, when detected early can often be removed during colonoscopy. Nevertheless, individuals at greatest risk of developing colorectal cancer remain largely under screened. This is due, in part, to poor public awareness and acceptance of current screening techniques. In fact, about half the patients that are eligible to be screened do no get screened.
Risk Factors: A personal or family history of colorectal cancer or polyps, and inflammatory bowel disease have been associated with increased colorectal cancer risk. Other possible risk factors include physical inactivity, high-fat and/or low-fiber diet, as well as inadequate intake of fruits and vegetables. Recent studies have suggested that estrogen replacement therapy and non-steroidal anti-inflammatory drugs such as aspirin may reduce colorectal cancer risk. The risk for colon cancer increases with age and screening is recommended for anyone 50 years or older.
Early Detection: The American Cancer Society recommends screening beginning at age 50 for both men and women. As of March 2008, the ACS includes virtual colonoscopy (VC) as one of the recommended colon cancer screening tests. Virtual colonoscopy should be repeated every 5 years if normal and a conventional colonoscopy should be performed if VC is abnormal (ACS Screening Recommendations). The other recommended tests are the following: a fecal occult blood test (FOBT) and flexible sigmoidoscopy (if normal, repeat FOBT annually, and flexible sigmoidoscopy every 5 years), double contrast barium enema (if normal, repeat every 5 years), or colonoscopy (if normal, repeat every 10 years). A digital rectal examination should be done at the same time as VC, sigmoidoscopy, colonoscopy, or double-contrast barium enema. These tests offer the best opportunity to detect colorectal cancer at an early stage when successful treatment is likely, and to prevent some cancers by detection and removal of polyps.
People should begin colorectal cancer screening earlier and/or undergo screening more often if they have a personal history of colorectal cancer or adenomatous polyps, a strong family history of colorectal cancer or polyps, a personal history of chronic inflammatory bowel disease, or if they are a member of a family of a hereditary colorectal cancer syndromes.
Some of the symptoms of colon cancer include blood in the stool, changes in bowel habits, decreased appetite, or fatigue. Although people with a family history may be at risk of colon cancer, many cases of cancer arise in people who have NO family history and NO noticeable symptoms. This is another reason why screening is so very important. For further information pertaining to colon cancer and related topics, please follow this link to the Gastroenterology department at the University of Chicago.
Why Screen with a Virtual Colonoscopy
Although the Barium Enema and Conventional Colonoscopy are exams of the entire colon, the sensitivity of barium enema varies greatly with the experience of the radiologist and is uncomfortable. Conventional Colonoscopy is the most accurate test for detection of polyps, but is associated with increased risk of complications and expense. About 2-5% of the time conventional colonoscopy cannot see the entire length of the colon. It may also cause an injury to the colon (tear or perforation) in one out of 1500 patients. Conventional Colonoscopy requires medication be given into the vein to make you sleepy and make the exam tolerable, therefore an hour or so of rest is needed after the exam and you should not drive yourself home.
Virtual colonoscopy is considered safe, non-invasive and a good screening test. It is well accepted by patients. They like the fact that the test takes 15 minutes and the computer does the rest. You can get up and drive home afterwards. This is why we have vigorously pursued research on virtual colonoscopy and offer it to patients for colorectal cancer screening. We still recommend conventional colonoscopy for patients with a high risk of colon cancer. High risk individuals who can not undergo conventional colonoscopy or whose physician recommends virtual colonoscopy for some reason, may also be screened with CT virtual colonoscopy. High risk patients include those with a personal history of colon cancer, a close relative who had colorectal cancer before age 60, a history of pre-malignant adenomatous polyps in the colon, a history of ulcerative colitis and certain family syndromes.
While there are many benefits to using virtual colonoscopy to screen for colon cancer, there are some limitations of this technique. Since it is a non-invasive test, it cannot be used to remove any polyps that are found. This is why at the University of Chicago patients are often offered same day conventional colonoscopy if their virtual colonoscopy shows polyps that need removal. Virtual colonoscopy is also not perfect at detecting small polyps less than 6mm in size. However, the vast majority of these small polyps (more than 99%) are not pre-cancerous and do not need to be removed. The cancerous potential of a polyp is directly related to its size (the bigger the polyp the higher the chances of it being cancerous). Also, polyps tend to grow very slowly over years. This is why small polyps can safely be monitored for growth with regular follow-up screening without having to remove them with the more invasive conventional colonoscopy. Flat polyps that do not protrude into the bowel lumen may also be difficult to find on virtual colonoscopy. However, many of these flat and small polyps are also missed during conventional colonoscopy. In fact, because of advances in technology and software used in virtual colonoscopy, it may be better than conventional colonoscopy in finding these polyps.
Follow-up screening after a virtual colonoscopy is similar to that after a conventional colonoscopy and depends on the findings. If no polyps are found, patients are asked to repeat the test in 5-10 years. If 1 or 2 small polyps are found, it is considered safe to monitor them with a repeat screening in about 3 years. If more small polyps or a single large polyp are detected, patients undergo a conventional colonoscopy to remove them and can have a follow-up virtual colonoscopy in 5 years. Since virtual colonoscopy is a relatively new procedure, the standards for follow-up have not been universally adopted and may vary with each individual patient case.
How is Virtual Colonoscopy Done
Virtual Colonoscopy uses a low radiation dose helical (or spiral) computed tomography (CT or CAT scan) of the abdomen, which allows a radiologist 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 and several mild preparation choices are available (Bowel Preparation section). 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, thin, flexible plastic tube placed in the rectum, so that carbon dioxide gas (or room air in some cases) can be introduced in a safe manner using a pressure controlled mechanical pump. A very low x-ray dose CAT scan is then performed while the patient lies on their back and then again on their stomach. The patient needs to remain motionless and hold their breath for about 15 seconds in each position to improve picture quality. The total time required for the study is approximately 15 minutes of which about 5-7 minutes are uncomfortable due to the filling of the colon with gas. There may be mild cramping while the colon is filled and a few patients have severe cramping which goes away immediately on completion of the exam. 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 after the procedure. We offer the choice of remaining in the department for about 1-2 hours while the scan is read by the radiologist. If the scan shows a large polyp or mass, we offer same day referral to conventional colonoscopy, performed by the gastroenterologist (a bowel specialist) for biopsy or removal of the polyp(s) or mass.
Is it Painful
When gas or air is introduced in the colon some patients experience minimal temporary abdominal cramping or “gas pain”. We generally use carbon dioxide which is absorbed faster than air and makes you comfortable as soon as the exam is over. An intravenous injection of glucagon, a widely used medicine to relax the bowel can also be given to help reduce gas pain. We ordinarily do not use glucagon since the discomfort is brief and mild to moderate for most patients.
Is it Safe
Virtual colonoscopy is a very safe procedure and is considered safer than conventional colonoscopy but has some small risks. Some patients may experience a brief feeling of sweating and feeling faint during the distention phase of the exam. This is called a “vasovagal reaction” and occurs about 1% of the time. The feeling goes away after lying down for a few minutes.
Perforation of the colon is rare (0.0046% in a large survey of experts doing virtual colonoscopy) and is usually detected by the CT scan during the exam. Some of these rare perforations give no symptoms at all and patients are merely observed overnight for their safety. Symptomatic perforations are very rare and could require surgical repair.
The radiation dose for a virtual colonoscopy is much less than for a routine CT scan. However, pregnant women should not undergo virtual colonoscopy. The risk of not screening for colorectal cancer is much greater than the radiation risk of a low dose CT scan. For patients 50 years of age or older the use of CT is appropriate for colorectal cancer screening.
The preparation for virtual colonoscopy includes a colon cleansing. We prefer to use a saline cathartic in the form of magnesium citrate or phosphosoda. People with impaired renal function or cardiac disease should ask about an alternate preparation with a reduced volume of polyethylene glycol instead. Current research in virtual colonoscopy is exploring “fecal tagging” techniques with contrast material that may eliminate the need for colon cleansing in the future. This method will involve an alternate bowel prep strategy with the patient consuming several small doses of the contrast material solution, either iohexol or barium-sulfate, during the two days just prior their virtual colonoscopy. Even though using oral contrast for virtual colonoscopy is a relatively new method, oral contrast material has been used in radiology for many years and is safe and well tolerated by patients.
How to Go About Getting a VC
There are several ways to get a colonoscopy test, as described below. If you require any further assistance or have any questions, please feel free to Contact Us.
The University of Chicago currently has a clinical trial that offers a virtual colonoscopy at no cost to the patient. This trial only accepts patients who have a history of colon or rectal cancer and have undergone curative resection or excision within the last 6-24 months. The trial compares the standard of care procedures of optical (standard) colonoscopy and CT scan to the virtual colonoscopy. Therefore, patients must be willing to undergo CT scan, virtual colonoscopy, and standard colonoscopy in the same day. The coordinator takes care of all scheduling details. The study does not accept patients with any known metastases, those who have a current diverting loop ileostomy, a history of IBD, or that are pregnant. For additional information, please contact Katy Ceryes at 773-702-9743.
Screening (Self-Pay) Virtual Colonoscopy
For patients who meet American Cancer Society guidelines of-average risk-for colon cancer, you may self-pay ($3,084, of which a 25% discount is offered) and obtain a virtual colonoscopy. Generally this means you:
- are 50 years of age or older;
- do not have symptoms of colon cancer;
- do not have documented occult blood in the stool (you may have visible blood from hemorrhoids); and
- do not have a brother, sister or parent who had colon cancer.
Call our registration team at 773-795-9723, who will go through a checklist with you and answer your questions. They will send you a card to test your stool for blood. You will be given instructions on how to pay and how to schedule your tests.
Insurance-Billed VC for Incomplete Colonoscopy Or Patients Who Cannot Undergo Colonoscopy
Patients who have an incomplete colonoscopy at The University of Chicago, are offered a same-day VC if their colonoscopy is incomplete. The patient is already prepared so by doing it on the same day, the patient avoids the need for another prep and another day off from work. This is a particular advantage to having your conventional colonoscopy done at the University of Chicago. For more information about how to make an appointment with a gastroenterologist please see the Gastroenterology at the University of Chicago website. We believe that in our hands, virtual colonoscopy is the best test to evaluate for polyps and masses in patients who have an incomplete colonoscopy or who cannot undergo colonoscopy or who refuse colonoscopy. Insurance is billed for these VC exams, as a non-infused CT of the abdomen and pelvis. If you have had a VC here under these circumstances and insurance refuses to pay, please contact our registration team at 773-795-9723. Traditionally, patients who have had an incomplete colonoscopy would undergo a barium enema.
Will My Insurance Pay For Virtual Colonoscopy?
Virtual Colonoscopy for screening is not currently reimbursed by most insurance companies, but some do. Some companies pay for virtual colonoscopy if it is done for diagnosis (signs or symptoms) especially after an incomplete optical colonoscopy. As a result, patients calling for a screening virtual colonoscopy will have to assume the cost of the procedure themselves (unless they can determine that their insurer does cover it) – a $3,084 charge. This charge has 2 components a) the hospital charge (payable to “The University of Chicago Hospital”) and b) the radiologist charge (payable to “The University of Chicago Physicians Group”).
Will My Insurance Pay For Conventional Colonoscopy Done To Evaluate An Abnormality Found On The Virtual CT Colonoscopy Exam?
If you choose to have a same-day optical colonoscopy, we need to know some additional information beforehand. You will be given information about some additional restrictions during the colon preparation (e.g. no colored liquids) and the need to stop some medications like blood thinners. A request form will be sent (usually faxed) to your doctor to fill out. This is needed to gain information about things that might affect the colonoscopy, such as need for prophylactic antibiotics (e.g., patients with a heart valve or artificial joint) or whether you have a pacemaker or defibrillator (that affect use of devices to remove polyps). Our coordinator will give your insurance information to the gastroenterology clinic to help expedite pre-approval by insurance, if possible. Additional questions about insurance for conventional colonoscopy can be directed to the Gastroenterology Business Representative (773-702-2122).
You can always choose to have optical colonoscopy scheduled at a future date. That exam does involve sedation and normally you will need someone else to take you home after the exam since you may not drive or operate machinery on the same day that you have sedation. The department of gastroenterology will give you more information about that.
Medicare patients. Patients with Medicare will be required to sign a waiver informing you that virtual colonoscopy is a non-covered service (when done for screening), and you will accept responsibility for the payment in full. Your Medicare carrier will be initially billed and upon denial of the claim, which we expect, you will be billed directly. Medicare often does pay for virtual colonoscopy when done to evaluate an abnormality (such as blood in the stool or a low blood count) if performed after a failed attempted conventional colonoscopy.
Medicare may start covering virtual colonoscopy for screening in the near future. On December 20, 2007, U.S. Representative from Wyoming Barbara Cubin introduced legislation (H.R. 4879) to promote access to this form of colon cancer screening and mandate coverage of the test by Medicare. The bill also proposes to waive patient co-pays for VC if the test is done within 6 months of enrollment in Medicare, just like what is currently done for colonoscopies and mammograms (Full story).
Whom Do I Call To Schedule A Virtual Colonoscopy At The University Of Chicago?
Call our registration team at 773-795-9723. They will go through a questionnaire, send you the necessary forms and answer your questions.
Before you call please prepare the following information to expedite your call:
- Your medical and family history
- Medication list
- Know whether you are undergoing screening or diagnostic virtual colonoscopy
- If you are undergoing diagnostic virtual colonoscopy, you will need a prescription from your referring doctor. Please have that doctor’s contact information available.
- Insurance or Medicare information
If you do not know some of the above, please call anyway and we will try to assist you.