Getting a colonoscopy is one of the most important things you can do to prevent or spot colon cancer. Some people are hesitant to undergo a colonoscopy because of the preparation involved before the procedure. You must go on a clear-liquid diet for 24 hours and take a laxative the night before the procedure. But the temporary inconvenience is well worth the risk as colonoscopy can save lives. Here’s how to know if you need a colonoscopy.