CPT code 0364U identifies the clonoSEQ® Assay, a proprietary next-generation sequencing (NGS) test used to detect and monitor minimal residual disease (MRD) in hematolymphoid malignancies via blood or bone marrow specimens. As a PLA code tied to a single manufacturer's assay, it standardizes reporting for a clinically important monitoring tool that can influence treatment decisions and long-term surveillance strategies nationwide. The code matters nationally because MRD status increasingly informs prognosis and therapy selection in hematologic cancers, and clear coding affects coverage, billing consistency, and clinical documentation.

Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical purpose and service characteristics, payer coverage patterns and benchmarks, applicable billing modifiers and service-line implications, and the clinical context for repeat testing to track disease burden. The publication also summarizes common questions payers consider for NGS-based MRD assays, practical implications for lab and outpatient settings, and where to find additional policy updates. Data not available in the input is noted where relevant.