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Q&A: How are primary and admission ICD-10 diagnoses coded in the SNF setting?

Question: In our electronic health record (EHR), we have to code the primary diagnosis and admission diagnosis. I have heard conflicting answers as to how these should be coded. How are primary and admission ICD-10 diagnoses coded in the SNF setting?


Admission and principal diagnosis selection may depend on the resident’s status in the facility. For a short-term resident, admitted for skilled services, the admission and principal diagnosis may be the same. It should be the main reason the resident was admitted to your facility for the short-term services. The admission and principal can be the same diagnosis, but they can also be different. Many times, the admitting diagnosis is the condition that caused the resident to come to a facility versus being able go directly home. Think of it this way, not every person who develops pneumonia has to go to a nursing home—what is the condition that is causing them to come to a facility? Perhaps it really is the pneumonia, but maybe it’s an underlying chronic condition that is the reason for the admission to the SNF rather than treatment at home.

For a long-term resident it is a little different, especially when billing for a Medicare B therapy service. The official coding guidelines are used across all provider types, but were initially developed for the inpatient hospital setting. So, when it refers to “admission” in the coding guidelines, the provider type must also be considered. For a long-term resident, the principal and admission diagnosis are going to be the same diagnosis, which will be the main diagnosis that is causing the resident to require long term care. Even if this resident is receiving Med B therapy services, the principal diagnosis and admitting diagnosis are going to be that chronic condition requiring LTC. The first secondary diagnosis will be the reason for Med B therapy Services. The admitting diagnosis MAY change during a resident’s stay, especially if they came in initially for short term, but a long stay was determined after the skilled services were provided. It is important to check with your MAC about the requirements for coding the Admitting Diagnosis on the claim as they may have specific instructions.

Unfortunately, there are no free public documents that states all this clearly. This information is found in the American Hospital Associations Coding Clinic, which is a paid subscription. Members of AHIMA can find this information on the AHIMA website as well by searching for ICD-10 coding guidelines for Long Term Care.

AANAC also offers a ICD-10 Virtual Workshop.

Want to read more FAQs? Visit the AANAConnect community , where 14,000+ of your peers and experts in long-term care are asking and answering tough questions just like this.

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