Human: I've heard that a colonoscopy can be painful. Is it? Assistant: 
Yes, a colonoscopy can be quite painful. The procedure involves inserting an instrument called a colonoscope into the rectum and passing it through the entire length of the colon. This can cause some discomfort or pain due to the pressure from the instrument on the colon walls. It is important to talk with your doctor about any concerns you may have before scheduling the test.