Principal Diagnosis Selection for Patients Admitted for Cancer Treatment

by Andrea Houghton, MPH, RHIA, CCS, CCS-P, CDIP

My last blog talked about an advanced type of immunotherapy for patients suffering from cancer called Chimeric Antigen Receptor T-cell therapy where a patient’s own T cells are modified outside of their body to be able to recognize and destroy tumor cells.

In this environment of ever-changing treatment modalities available to cancer patients, it is helpful to review this gem from the ICD-10-CM Official Coding Guidelines for Coding and Reporting (FY 2018 Chapter 2: Neoplasms Section E, 2):

Patient admission/encounter solely for administration of chemotherapy, immunotherapy and radiation therapy

If a patient admission/encounter is solely for the administration of chemotherapy, immunotherapy or external beam radiation therapy assign code Z51.0, Encounter for antineoplastic radiation therapy, or Z51.11, Encounter for antineoplastic chemotherapy, or Z51.12, Encounter for antineoplastic immunotherapy as the first-listed or principal diagnosis. If a patient receives more than one of these therapies during the same admission more than one of these codes may be assigned, in any sequence.

This guideline is really important to remember, particularly if patients are being admitted for multiple types of treatment.

For example, if a patient is admitted for both chemotherapy and radiation therapy either Z51.11 or Z51.0 may be sequenced first if documentation supports they both meet the definition of a principal diagnosis. A word of caution: the selection of principal diagnosis between these two Z codes may affect your DRG!

Similarly, a patient may receive immunotherapy and chemotherapy during the admission and either may be selected as your principal diagnosis if both meet the definition of principal diagnosis. In this case, the DRG would most likely be the same.

Keep this Official Coding Guideline in mind when you are coding patients who are admitted to the hospital for cancer treatments. It will help you determine the most appropriate principal diagnosis for your patient population.


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About the Author

Andrea Houghton, MPH, RHIA, CCS, CCS-P, CDIP
Andrea Houghton has over twenty years’ experience participating in various roles in health information management including coding, auditing, and compliance. She currently is the Coding Manager for Lucile Packard Children’s Hospital Stanford. She also works for CHIS, Inc, a consulting firm specializing in providing coding services to the University of California at San Francisco.

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