Medicare's billing code for a yearly wellness exam is G0438 for a patient's first wellness exam under Medicare and G0439 for each subsequent annual exam. Medicare's billing code for a preventative colonoscopy is G0105.
Billing for Medicare always involves at least one CPT and one ICD-9 code. CPT codes refer to specific procedures, and ICD-9 codes signify diagnoses. Medicare billing requires that a diagnosis code demonstrate medical necessity for the procedure in question.
In the case of wellness exams, Medicare requires V70.0 be affixed to the exam code. For preventative colonoscopies, Medicare permits that V76.51, V16.0 or V12.72 diagnosis codes be affixed to G0105.