What is the correct CPT code for diagnostic arthroscopy of the shoulder with acromioplasty?

The correct CPT code for diagnostic arthroscopy of the shoulder with acromioplasty is 29826. This code specifically encapsulates the procedures of both diagnostic arthroscopy and acromioplasty, which involves the surgical reshaping of the acromion to relieve impingement or other shoulder problems.

The other options do not accurately represent the combination of procedures being performed. For instance, codes 23415 and 23420 refer to various repairs of the shoulder, such as a rotator cuff repair, and are not applicable in the context of diagnostic arthroscopy combined with acromioplasty. The code 29827, on the other hand, is for more extensive shoulder procedures that do not align with the actions described in the question. Therefore, 29826 is the appropriate choice because it covers both the diagnostic aspect and the surgical procedure of acromioplasty done via arthroscopy, reflecting the comprehensive nature of the treatment provided.