Cracking the Code

Coding ‘History of’

There are two types of history: personal history and family history. Family history is important to report because some diseases have a genetic predisposition. For example, female patients with a family history of breast cancer are at a higher risk for developing breast cancer. Family history codes can be found in our ICD-10-CM Alphabetic Index under History/family (of).


Personal history codes are reported if the patient no longer has the disease. A history of an illness, even if no longer present, is important information that may alter the type of treatment ordered. We can locate personal history codes in our ICD-10-CM Alphabetic Index under History/personal (of).


History codes have an entry in the ICD-10-CM guidelines. These can be found at I.C.21.c.4. It is important for all coders and auditors to apply these codes when applicable.


Remember, the reason for the encounter (for example, screening or counseling) should be sequenced first and the appropriate personal and family history codes should be assigned as additional diagnoses.

Q: A patient’s dense breast tissue has made the screening mammogram unreadable, and she is here today for a breast ultrasound. Her mother and sister both have a history of breast cancer. What are the ICD-10-CM codes for this encounter?
A: Z12.39, R92.2, Z80.3 Rationale: We are going to code for the special screening as a reason for the encounter, along with a code to report the patient’s breast density, which provides the medical necessity for a more extensive test. Dense breast tissue occurs in many premenopausal women and can interfere with reading a mammogram and may mask abnormalities in the image. We are going to look at the ICD-10-CM Alphabetic Index for Screening/neoplasm (malignant) (of)/breast Z12.39. For the breast density, let’s look at the Alphabetic Index for Dense/breasts, bringing us to R92.2. This code provides medical necessity of an ultrasound. To report the family history of breast cancer, we look in the Alphabetic Index under History/family (of)/malignant neoplasm (of)/breast Z80.3, which may provide medical necessity information for the screening exam in a young patient. As always, we are going to verify all codes in the Tabular List.
Reference: FY 2023 ICD-10-CM code book & guidelines
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