https://www.cancer.org/cancer/colon-rectal-cancer/detection-...
For asymptomatic people without abnormal stool, colon cancer tests are called "screening," never "diagnostic." "Screening" is covered without cost sharing. Colonoscopy, fecal tests, etc.
>But if you have a screening test other than colonoscopy and the result is positive (abnormal), you will need to have a colonoscopy. Some insurers consider this to be a diagnostic (not screening) colonoscopy, so you may have to pay the usual deductible and co-pay.