A colonoscopy uses a camera to look at the whole of the inside of the large bowel as shown in purple on the diagram. You have this test in the endoscopy department and it takes about an hour. The bowel needs to be empty for the test, so you would be given strong laxatives to take at home the day before the test.
You nearly always have a colonoscopy with sedation and painkillers because it would be uncomfortable without them. You may be able to have a colonoscopy without a sedative if you have particular reasons for wanting to do so. You would need to talk to your doctor beforehand about this.
During the colonoscopy you may have some level of conciousness but the examination should be kept as comfortable as possible. If polyps are found in the bowel they are usually removed during the test. If a cancer is found this will be biopsied and its position marked in the bowel with a special tatoo ink
You should be able to go home a couple of hours after the test. You shouldn't drive for about 24 hours after having the sedative. If you have had a sedative you must have someone with you to take you home. If you live alone, ideally they should stay overnight just to make sure that you are all right.
Virtual colonoscopy is also called CT colonography. Instead of having the colonoscope put inside your bowel, the doctor looks at pictures created by a computer. Before the test you have laxatives and plenty of fluids to clear out your bowel. You also follow a special diet for a couple of days beforehand. Your doctor or nurse will give you full details. The test uses a CT scanner, so you have this test in the CT scanning department. Just before the test the doctor or nurse puts a small tube into your back passage to pump air or carbon dioxide inside. This helps to open up the bowel, which gives clearer pictures on the scan. A computer then creates a 3D reconstruction of the inside of your bowel. This shows up any growths on your bowel wall. If a growth is found you will still need a colonoscopy to biopsy or remove it.