When an admission is specifically for treatment of anemia associated with an adverse effect of chemotherapy or immunotherapy, and treatment is directed only at the anemia, the anemia diagnosis is sequenced first.
The FY 2026 ICD-10-CM Official Guidelines distinguish chemotherapy-related anemia from anemia caused directly by the malignancy. For chemotherapy-associated anemia, the anemia code is sequenced first, followed by the appropriate neoplasm code and the applicable adverse-effect code for the antineoplastic drug.
This differs significantly from anemia associated with the malignancy itself. If the patient is admitted solely to manage anemia caused by the malignancy, the malignancy is sequenced first, followed by the anemia-in-neoplastic-disease code.
The adverse-effect code is required to explain the medication-related cause, but it is not sequenced before the manifestation in this scenario because adverse-effect coding follows the nature of the adverse effect first.
For CDI specialists, accurate documentation of the cause of anemia—malignancy, chemotherapy, bleeding, chronic disease, nutritional deficiency, or another condition—is therefore essential because etiologic specificity can directly change sequencing.
CCDS Reference Topics: Chemotherapy adverse effects; anemia; neoplasm coding; principal diagnosis; sequencing.
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