Several routine procedures are considered preventative. Many insurance companies cover preventive exams and procedures 100%, meaning there is no out-of-pocket cost to you.
If there's a specific problem being addressed during a routine medical procedure, it is considered diagnostic. For a diagnostic procedures, your usual copay, deductible and coinsurance apply.
Sometimes preventative procedures can become diagnostic. For example, if polyps are discovered during a routine preventative colonoscopy, the physician will likely remove them. At that point, the colonoscopy becomes a diagnostic procedure instead of a preventive procedure.
Review your insurance plan for coverage details.