Q&A: Coding gangrene in a patient with a history of diabetes

Q: We recently had a patient with a history of diabetes admitted with gangrene of the left second toe. Can I use code L97.529 for this case?

A: Based on the limited information provided, I cannot recommend code assignment for this case but let’s review a few rules related to coding and documentation that might help you.

First, if the type of diabetes is not documented by the provider, code assignment defaults diabetes mellitus type II. Ulcers of the digits of the foot are usually classified as diabetic ulcers, but if there is documentation in the medical record that would lead you to believe the ulcers are not related to the diabetes, a query may be necessary for clarification. Also, if there is any evidence in the medical record that indicates the gangrene is not related to the diabetes, query the provider.

When coding any non-pressure chronic ulcer classifiable to L97-, code first the underlying cause of the ulcer, if known, followed by the appropriate L97- code to identify the ulcer location, site, and severity. Any gangrene associated with the ulcer should also be coded first (prior to the sequencing of the L97- code). Skin ulceration in a diabetic patient is assumed to be related to the diabetes, unless specified by the provider.

Also review Section 1.A.15 of the Official Guidelines for Coding and Reporting, which states:

The word “with” or “in” should be interpreted to mean “associated with” or “due to” when it appears in a code title, the Alphabetic Index (either under a main term or subterm), or an instructional note in the Tabular List.  The classification presumes a causal relationship between the two conditions linked by these terms in the Alphabetic Index or Tabular List. These conditions should be coded as related even in the absence of provider documentation explicitly linking them, unless the documentation clearly states the conditions are unrelated or when another guideline exists that specifically requires a documented linkage between two conditions (e.g., sepsis guideline for “acute organ dysfunction that is not clearly associated with the sepsis”). 

For conditions not specifically linked by these relational terms in the classification or when a guideline requires that a linkage between two conditions be explicitly documented, provider documentation must link the conditions in order to code them as related.

The word “with” in the Alphabetic Index is sequenced immediately following the main term, not in alphabetical order.

When you look up the condition “diabetes” in the Alphabetic Index, you will find directly underneath the main bolded term of diabetes the word “with.” When continuing down the page, you will find code E11.621, Foot ulcer, and directly beneath that, code E11.52, Gangrene.

When you look up code E11.621, Type 2 diabetes with foot ulcer, there is a convention that states use additional code to identify site of ulcer (L97.4-, L97.5-).

Editor’s Note: Sharme Brodie, RN, CCDS, CDI education specialist and CDI Boot Camp instructor for HCPro in Middleton, Massachusetts, answered this question. For information, contact her at sbrodie@hcpro.com. For information regarding CDI Boot Camps, click here.