Final answer:
The coder should review the operative notes to assign the code for the extensive drainage procedure.
Step-by-step explanation:
Prior to assigning the code for the extensive drainage, the coder should review the operative notes. The operative notes contain important details about the procedure, including the extent of the drainage performed. By reviewing the operative notes, the coder can ensure that the correct code is assigned based on the specific details of the procedure.
For example, if the operative notes mention that the drainage involved multiple sites or extensive tissue removal, it may warrant a different code compared to a less extensive drainage procedure.
Therefore, reviewing the operative notes is crucial for accurate coding and billing.