Is it an individual or a group plan? A few things to think about:
1.) If it is an individual plan, read the plan document carefully. Many states mandate cancer screenings like mammograms and prostate screenings and that's it. Other plans say they will pay for preventive care (such as the office visit) upto $300.00/year but only AFTER the deductible is met. And lab and x-ray that is not done in the doctor's office typically will apply to your deductible.
2.) Here is another gotcha. If you talk about anything but your preventive care during your preventive exam with your doctor, you doctor is going to bill the visit as ROUTINE care vs. PREVENTIVE care, which could cause your insurance carrier to apply the visit to the deductible instead of paying for the visit without it being subject to the deductible. I had that happen to me firsthand on my HSA plan the first year I got it, and it wasn't the insurance company's fault. I talked to my doctor about acid reflux during my preventive exam, so she billed it as "routine" instead of "preventive". Thus the visit applied to my deductible instead of being paid without being subject to the deductible. When I complained to the doctors office, they refused to rebill the claim as preventive and told me if I had wanted to talk about non-preventive care during my office visit, I should have made a separate appointment.
3.) Group plans typically have better preventive coverage than individual plans, because they almost always pay for the office visit 100% after copay.
4.) Lastly, don't expect your insurance carrier to pay for a preventive colonoscopy without meeting your deductible first. Colonoscopies almost always hit the deductible before coverage kicks in. Some carriers are starting to pay for Colonoscopies upfront, but not very many yet. And...some individual plans do not cover preventive colonoscopies at all. In that case, you should see if your doctor will bill it as diagnostic instead of preventive. Then, it will be covered, but likely subject to the plan deductible first.