Evaluation of the Colon Beyond an Obstructing Lesion
In approximately 5 percent of colorectal cancer cases, there is more than one tumor present at the same time. It is also very common for two polyps to be present at the same time (49). Occasionally, a cancer is identified in the lower colon that may prevent the doctor from continuing the colonoscopy procedure into the upper colon. In these situations virtual colonoscopy has been shown to be useful in evaluating the upper colon for additional lesions (49). A potential limitation of virtual colonoscopy in these types of cases is getting the colon near the tumor clean enough to allow for a good enough evaluation. However, in our experience an optimal evaluation is usually possible.