They aren't supposed to do this - See the link I posted on a sibling comment
https://www.cancer.org/cancer/colon-rectal-cancer/detection-...
>Soon after the ACA became law, some insurance companies considered a colonoscopy to no longer be just a ‘screening’ test if a polyp was removed during the procedure. It would then be a ‘diagnostic’ test, and would therefore be subject to co-pays and deductibles. However, the US Department of Health and Human Services has clarified that removal of a polyp is an integral part of a screening colonoscopy, and therefore patients with private insurance should not have to pay out-of-pocket for it (although this does not apply to Medicare, as discussed below).
