Recurrent Thorcentis

What CPT code would be used for the recurrent Thoracentesis for pleural effusion through a pleurx catheter 32421 or 32422 ? We have billed to Medicare using the 32421-52 with our physician's logic that the catheter was previously placed and these are subsequent Thoracentis hence the use of the 52 modifier as the catheter was not placed at each visit. Our physician's documentation as follows:

Procedure:Thoracentesis through a pleurx catheter
Indication: Recurrent pleural effusion
Procedure: Through the patient's existing pleurx catheter, 900 cc of pleural fluid was drained under sterile condition. The patient tolerated the procedure well.

I think it should be 32422 without the 52 modifier as by the description in the Coder's desk reference the catheter may be connected to a water seal system to allow continuous or intermittent removal of fluid.
The description of the 32421 is for puncture insertion of a needle to withdraw fluid and does not mention a catheter being present.

Anyone's experience with this situation or opinion would be greatly appreciated.

Thank you,
Joyce Talbert CPC