CPT code 86920 denotes an immediate spin crossmatch—a rapid laboratory test to assess compatibility between patient serum and a donor blood unit before transfusion. This code is clinically important because it supports safe, timely blood transfusions in inpatient and urgent outpatient settings and is widely used across hospitals and clinical laboratories nationally. Payers commonly involved in coverage and reimbursement for this service include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will learn what the code represents clinically, where the service is performed, and the payer landscape relevant to coverage. The publication provides benchmarks where available, explains clinical context for when an immediate spin crossmatch is used versus other compatibility testing methods, and summarizes policy and coding considerations that affect billing and reimbursement nationally. Data not available in the input for associated taxonomies, detailed payer-specific rates, and linked ICD-10 diagnoses are noted where applicable.