CPT code 35820 denotes surgical reopening of the chest to identify and control postoperative bleeding, clotting, or infection after an earlier thoracic operation. Nationally, this code signals an emergent or urgent return-to-the-operating-room scenario with significant implications for patient safety, hospital resource use, and postoperative quality metrics. Payers commonly involved in coverage decisions for this service include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.

Readers will find a concise explanation of the clinical intent of CPT code 35820, typical settings where the service is furnished, and the payer landscape relevant to billing and coverage. The publication provides benchmarks and payment context, outlines common modifiers and billing considerations, and highlights clinical scenarios that commonly prompt use of the code. It also summarizes policy items and coding guidance that affect national reimbursement and reporting for re-entry thoracic procedures. This overview is aimed at coding professionals, hospital billing teams, and policy analysts seeking a clear, nationally-focused reference for CPT code 35820.