Summary & Overview
CPT 81268: Post‑Transplant STR Chimerism Testing, Lineage‑Specific
CPT code 81268 is a laboratory molecular diagnostic procedure used to compare STR markers from a post‑transplant specimen with the original donor specimen (initial donor testing reported in 81265) to determine chimerism or engraftment and to detect disease recurrence. This test is clinically important for monitoring hematopoietic stem cell and bone marrow transplantation outcomes, guiding further therapeutic decisions, and informing surveillance strategies after transplant. Nationally, CPT code 81268 supports tracking of transplant success and relapse detection across transplant centers and reference laboratories.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the clinical purpose of the code, common billing and service contexts, and what typical site of service and service type entail. The report also outlines commonly used modifiers and situational billing considerations where data are available. It provides clinical context about lineage‑specific testing such as CD‑3 positive T‑cell analysis and explains why this testing matters for post‑transplant monitoring. Data not available in the input are noted where applicable.
Billing Code Overview
CPT code 81268 describes a laboratory molecular test that compares short tandem repeat (STR) markers from a post‑transplant specimen, such as bone marrow, with the initial donor specimen tested in 81265 to assess chimerism or engraftment and to detect disease recurrence. The procedure can include testing of lineage‑specific cell subsets such as CD‑3 positive T‑cells.
Service type: Laboratory molecular diagnostic test for post‑transplant chimerism/engraftment
Typical site of service: Clinical laboratory or hospital/academic laboratory processing bone marrow or blood specimens
Data not available in the input.
Clinical & Coding Specifications
Clinical Context
A 46-year-old patient with acute myeloid leukemia underwent allogeneic hematopoietic stem cell transplantation (bone marrow transplant). At scheduled post-transplant outpatient follow-up, the transplant team orders lineage-specific short tandem repeat (STR) chimerism testing to assess donor engraftment and to detect early disease recurrence. A peripheral blood sample is collected and sorted by flow cytometry to isolate CD3-positive T-cell and CD33-positive myeloid cell subsets. The laboratory performs technical STR analysis comparing post-transplant STR markers to the original donor specimen tested previously (reported under 81265) to quantify donor versus recipient cell proportions.
Clinical workflow:
-
Patient presents to outpatient transplant clinic for post-transplant surveillance.
-
Phlebotomy collects peripheral blood; laboratory may perform cell sorting for lineage-specific subsets (for example,
CD3T cells) before DNA extraction. -
Laboratory analyst performs STR amplification and fragment analysis to compare post-transplant specimen with the donor reference specimen, generating percent donor chimerism and reporting lineage-specific results.
-
Results are returned to the transplant physician to inform clinical decisions about immunosuppression, donor lymphocyte infusion, or further diagnostic workup for relapse.