Patients with Contraindications to Colonoscopy and Patients Who Refuse Other Screening Options
For a variety of reasons, a colonoscopist may be hesitant or unwilling to perform conventional colonoscopy in a patient with clinical symptoms (bleeding, change in bowel habits, etc.) that could indicate a tumor is present. Reluctance to perform colonoscopy may be related to advanced patient age, severe pulmonary disease, a bleeding disorder, or a prior allergic reaction to sedation during colonoscopy. In these cases, a virtual colonoscopy can be safely performed to exclude cancer.
Also, because of anxiety, fear, embarrassment, or misinformation, many people who should undergo screening are reluctant. Although conventional colonoscopy is the current gold standard for evaluation of the entire colon, it is useless if patients refuse to have it performed. The concept of a relatively noninvasive examination (virtual colonoscopy) that can image the colon and detect significant lesions is appealing to many patients. Once a suspicious lesion is detected, a patient will be more willing to undergo conventional colonoscopy and removal of the polyp.
It should be pointed out that virtual colonoscopy is not an entirely benign procedure. There has been some controversy in study reports regarding patient satisfaction and comfort levels with the examination (50-52). Our own evaluations of patient preferences for virtual and conventional colonoscopy are ongoing. When asked which procedure they preferred, 70.5 percent of our patients so far chose virtual colonoscopy while 29.5 percent chose conventional colonoscopy.
Another recent study of patients undergoing virtual colonoscopy followed by conventional colonoscopy demonstrated that, of those who had an opinion, 82 percent preferred virtual colonoscopy (51). Yet another recent study showed that 63.7 percent preferred conventional to virtual colonoscopy (52). How can these differences be explained? Some of it has to do with the CT technique. At NYU we feel strongly that patient comfort and privacy need to be maximized during virtual colonoscopy. We do not use IV catheters or needles for the procedure, while others may use bowel relaxants requiring IV access. Another important aspect of the way virtual colonoscopy is performed at our institution is that a small rubber catheter is used. This is quite different from a barium enema tip catheter. The difference in the diameter between the two catheters is 10 mm (5 mm vs. 15 mm). It is important to mention here that the outcomes of the exams—as well as the therapeutic effect of conventional colonoscopy in being able to remove polyps as well as detect them—may influence how patients feel about the two procedures. A patient may prefer virtual over conventional colonoscopy, but if the patient knows something can be done to remove a detected abnormality at colonoscopy right away, it may increase the patient’s acceptance of conventional colonoscopy.