Cerebral Infarction When Patient Has Carotid Stenosis

The Alphabetic Index

Confusion can arise when a patient has both carotid stenosis and a cerebral infarction based on the use of different sub-terms in the index depending on the main term the search begins with.

If the coder searches the terms, Stenosis, artery, and precerebral NEC (there is no specific subterm entry for carotid, but the carotid artery is a precerebral artery), the index directs the coder to “see Occlusion, artery, precerebral”.

A search of the index under the terms, Occlusion, artery, precerebral provides two relevant subterms “with infarction” and “carotid”. Since carotid stenosis was the original diagnosis being searched for, choosing the subterm “carotid” lends itself to finding the most specific code. At this subterm the index directs, “see Occlusion, artery, carotid”.

Once the terms Occlusion, artery and carotid are found, the index has further subterms “with” and “infarction” that direct the coder to assign a code from subcategory I63.23-. Application of the ICD-10-CM “With” convention seems to indicate a cause and effect relationship between carotid stenosis and cerebral infarction.

However, beginning a search of the index under the terms Infarct, infarction, cerebral provides a further subterm of “due to”, rather than “with”, and then occlusion NEC, precerebral arteries or due to, stenosis NEC, precerebral arteries. Both of these searches also directs the assignment of a code from subcategory I63.2-.

The Tabular List

As a matter of correct coding, any code directed for use by the index should be confirmed in the Tabular List and if the code in the Tabular does not appropriately describe the diagnosis being reported the coder should return to the index for additional review. Confirmation in the Tabular includes reviewing all instructional notes associated with the code, category or chapter the code comes from. In the case of carotid stenosis and cerebral infarction, regardless of the terms searched, the index directs the coder to assign a code from category I63 Cerebral Infarction, which includes the following specification,

What should the coder do?

The advice in Coding Clinic Third Quarter 2018, page 5, proposes a comparable scenario. In this case the patient has had an MI and has chronic total occlusion of a coronary artery other than the artery associated with the MI. ICD-10-CM has an Excludes1 note at I25.82, Chronic total occlusion of coronary artery, which excludes "acute coronary occlusion with myocardial infarction (I21.-, I22.-)." In this case separate codes for both the MI and the chronic total occlusion are assigned because the MI was caused by occlusion in a different artery.

Similarly, in a case of cerebral infarction with carotid stenosis, the coder should look at radiology imaging reports, progress notes and/or other pertinent documentation to find the location and cause of the cerebral infarction. If the infarction is due to the carotid stenosis, and it is documented as such, then the combination code from category I63 would be assigned. However, cerebral infarctions can be due to other causes, such as a thrombus or embolus, that are not related to carotid stenosis. Many patients have minimal carotid stenosis but have cerebral infarctions due to other causes. If the documentation indicates that the cerebral infarction is not associated with carotid stenosis because it is due to another cause, the combination code would NOT be assigned. Instead, the cerebral infarction would be coded according to the cause of the infarction with an additional code assigned for carotid stenosis if it is clinically significant. For example, if the patient has minimal stenosis of the right carotid artery and the patient has a thrombotic infarction of the right posterior cerebral artery, a code for carotid stenosis may not be necessary.

When a connection between the infarction and carotid stenosis is unclear, best practice would be to query the physician to determine if there is a link between the two conditions. If the facility does not allow query in these cases, assign separate codes for the carotid stenosis and cerebral infarction because the phrase “due to” in the code description (i.e. Cerebral infarction due to unspecified occlusion or stenosis of unspecified precerebral arteries) requires a documented cause and effect relationship in order to assign the combination code.

References
Coding Clinic, Second Quarter 2023, Page 17

Coding Clinic, Third Quarter 2018, Page 5

Coding Clinic, Third Quarter 2014: Page 5

ICD-10-CM Official Guidelines for Coding and Reporting

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The information contained in this post is valid at the time of posting. Viewers are encouraged to research subsequent official guidance in the areas associated with the topic as they can change rapidly.