CPT code 29871 represents arthroscopic irrigation and drainage of the knee joint to evaluate and treat suspected intra‑articular infection. As both a diagnostic and therapeutic procedure, it plays a critical role in early management of septic arthritis and other purulent joint processes; timely surgical washout can affect clinical outcomes and downstream resource use. Nationally, the code is relevant across hospital and ambulatory surgical settings where orthopedic and sports medicine specialists, as well as acute care surgeons, manage septic or suspected septic joints.

Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise review of the clinical context for use of the code, expected sites of service, and common billing considerations. The publication provides benchmarks and utilization context where available, summarizes relevant policy and coverage considerations that affect access and prior authorization, and outlines typical coding relationships to inpatient and outpatient surgical settings. Data not available in the input is noted where applicable. This summary is intended for billing managers, revenue cycle teams, clinical leaders, and policy analysts seeking a practical national overview of CPT code 29871 and its role in managing knee joint infections.