Final answer:
The appropriate CPT code for a diagnostic shoulder arthroscopy with synovial biopsy is 29821, corresponding to the specific procedure performed on the shoulder joint.
Step-by-step explanation:
Ron Jones, who has been experiencing left shoulder pain for six months, underwent a diagnostic shoulder arthroscopy with synovial biopsy. In order to select the appropriate code using the CPT manual, one must match the procedure to the defined CPT codes for shoulder procedures. The correct CPT code for a diagnostic shoulder arthroscopy with synovial biopsy is 29821. This code corresponds to an arthroscopic procedure involving the shoulder joint, including the biopsies of the synovium.