Abnormal complete blood count (CBC) ICD-10-CM coding
An ICD-10-CM code does not exist that specifically means “abnormal CBC” as a stand-alone diagnosis. Coding should be based on the specific abnormal CBC finding documented by the clinician. [1]
Default code when CBC abnormality is documented without a specific blood-cell type
When CBC results are documented as abnormal without specifying the abnormal component and no confirmed diagnosis is present, ICD-10-CM category R70–R79 (abnormal findings on examination of blood, without diagnosis) is used. [2]
Common nonspecific code used when details are insufficient
R79.9 — Abnormal finding of blood chemistry, unspecified is a frequently used nonspecific code in billing workflows when no more specific blood-test finding is documented. [3]
More specific alternatives when the abnormal CBC component is documented
More specific ICD-10-CM codes should be selected when the chart documents the abnormal component (for example, abnormal red blood cell findings vs abnormal white blood cell findings). [1]
Practical sequencing considerations
Abnormal-test “without diagnosis” codes in R70–R79 are used when the abnormal CBC is not yet tied to a confirmed condition. [2]
Documentation needed for accurate code selection
The clinician documentation should specify which CBC abnormality is present (red cells, white cells, platelets, hemoglobin/hematocrit, leukocyte differential abnormalities, or platelet count abnormality) to support selection of a more specific ICD-10-CM code rather than a nonspecific code. [1]