Excludes1 pair
D56.1 vs D56.2
D56.1 and D56.2 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.
The official note, declared on D56.1
delta-beta thalassemia (D56.2)
D56.1
Beta thalassemia
Billable
- Chapter 3
- Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism
- Section
- D55-D59
Use when the record says
- Beta thalassemia major
- Cooley's anemia
- Homozygous beta thalassemia
- Severe beta thalassemia
- Thalassemia intermedia
- Thalassemia major
Indexed under
- Cooley's anemia
- Anemia › Cooley's (erythroblastic)
- Anemia › familial erythroblastic
- Thalassemia › beta (severe)
- Thalassemia › intermedia
D56.2
Delta-beta thalassemia
Billable
- Chapter 3
- Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism
- Section
- D55-D59
Use when the record says
- Homozygous delta-beta thalassemia
Indexed under
- Thalassemia › delta-beta (homozygous)
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027