Doctors at NewYork-Presbyterian routinely screen patients for colon cancer employing several techniques including traditional colonoscopy, virtual colonoscopy, high-sensitivity fecal occult blood testing, and sigmoidoscopy. Traditional colonoscopy has long been considered the "gold standard" of colon cancer screening. In addition to being a direct screening method that accurately detects cancer, it allows for biopsy of precancerous cells and removal of polyps.
Patients begin the procedure at home by sticking to a clear liquid diet and drinking large quantities of a liquid preparation designed to empty the colon. Typically, patients drink half of the bowel prep the night before the colonoscopy, and the other half the morning of the procedure.
A traditional colonoscopy usually takes place in an endoscopy suite or office. First, an anesthesiologist will administer sedation and then a gastroenterologist will insert a colonoscope into the rectum to examine the entire length of the colon. The colonoscope consists of a flexible tube about 5ft long and 1cm in diameter with a light, camera, and a channel for doctors to pass instruments. It is inserted all the way to the top of the colon where the cecum is located, but it is during the withdrawal portion of the procedure that the colon is carefully examined for polyps and cancerous cells. It is important for gastroenterologists not to rush the withdrawal of the scope in order to accurately identify polyps. If polyps are found during the exam, they can be removed using a small lasso device and sent to the lab for testing. Doctors can also biopsy other abnormalities during the procedure. The colonoscope is able to visualize small polyps (less than 10mm in diameter).
Because patients have undergone sedation for the traditional colonoscopy, they are advised not to drive that day and have someone accompany them home from the exam. Otherwise, patients generally feel fine.
Traditional colonoscopy has long been considered the "gold standard" of colon cancer screening due to its ability to detect and remove polyps. However, because it is an invasive, time-consuming procedure that requires sedation, some patients may choose another screening method such as virtual colonoscopy.