CPT code 20931 covers the intraoperative placement of a structural allograft—donor bone used to fill bony defects—during spinal surgery. This code captures a discrete surgical supply and grafting service that can affect surgical planning, implant tracking, and hospital billing. Nationally, accurate coding for structural allografts matters for quality reporting, device and graft inventory, and alignment with payer coverage policies for spinal fusion and reconstruction.

Key payers in this overview include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of the clinical context for using a structural allograft in the spine, common sites of service, and the types of documentation that typically support billing for graft implantation. The publication also summarizes payer coverage considerations, billing modifiers commonly applied to surgical implant services (listed separately), and benchmarking notes where available. Data not available in the input is noted when applicable.

This report is intended for coding professionals, hospital billing managers, and clinicians involved in spinal surgery billing workflows who need a clear, national-level reference on what CPT code 20931 represents and how it fits into surgical service lines and payer interactions.