A21.1

Clinical notes

Documentation support

General coding-documentation guidance — not a substitute for payer-specific requirements or professional coding judgment.

• •As a general rule, code to the highest level of specificity supported by the documentation in the medical record.

ICD-9-CM equivalent

Informational only — GEM mappings are approximate, not guaranteed one-to-one equivalents. Verify before use in billing.

• 0213

Associated MS-DRGs

A21.1 can serve as the principal diagnosis for these Medicare Severity Diagnosis-Related Groups.

Informational only — actual DRG assignment also depends on procedures, complications/comorbidities (CC/MCC), discharge status, and payer-specific rules not reflected here.

• DRG 849Radiotherapy
• DRG 867Other Infectious and Parasitic Diseases Diagnoses with MCC
• DRG 868Other Infectious and Parasitic Diseases Diagnoses with CC
• DRG 869Other Infectious and Parasitic Diseases Diagnoses without CC/MCC