Here are two things you probably don’t know about colonoscopies. First, they’re one of the most commonly performed screening exams. Millions of us get colonoscopies each year, but we don’t like to talk about it. Second, you probably don’t know how much a colonoscopy costs, even if you are a patient who has scheduled an exam. That’s because colonoscopies are like most health care services: patients don’t know the cost in advance of receiving care.