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Question:  My podiatrist is treating a patient with diabetes who is also suffering from peripheral angiopathy. This patient has developed a severe stage 4 pressure sore on their right heel. Additionally, the wound has become gangrenous. I know coding the condition is complex, but what order should I list the codes in? Since their diabetes is a major contributing factor, is that coded first?

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Answer:  The first thing you’ll want to do is clarify what type of diabetes the patient suffers from. There are four types of specified diabetes groups and an unspecified category, each having their own code sets: E08 (Diabetes mellitus due to underlying condition), E09 (Drug or chemical induced diabetes mellitus), E10 (Type 1 diabetes mellitus), E11 (Type 2 diabetes mellitus), and E13 (Other specified diabetes mellitus).

If the provider doesn’t clarify which form of diabetes the patient has in the notes, or you are unable to verify which type even after querying the provider, do not use a code from E13. Instead, follow ICD-10-CM guideline, 1.C.4.a.2, which tells you to use a code from E11 as the default code. (For the purposes of this answer, E11 will also be our default code.)

Sequencing will be another important factor when coding this patient. Should you code diabetes, the pressure ulcer, or the gangrene first? ICD-10-CM guideline IV.G tells you to “list first the ICD-10-CM code for the diagnosis, condition, problem, or other reason for encounter/visit shown in the medical record to be chiefly responsible for the services provided” for all outpatient services. So, for coding this decubitus ulcer, you should use L89.614 (Pressure ulcer of right heel, stage 4) to identify the location, but you should also list E11.622 (Type 2 diabetes mellitus with other skin ulcer) first because L89.614 only identifies the location, not the connection between diabetes and the ulcer. Based on guideline I.C.4. a for diabetes, you should connect diabetes to all conditions listed under “with” in the index.

Then you need to decide what comes next: the diabetes, peripheral angiopathy, or the gangrene. Fortunately, there is one code that includes them all — E11.52 (Type 2 diabetes mellitus with diabetic peripheral angiopathy with gangrene). This would be the correct code instead of listing each separately.

Even though the gangrene is the principal diagnosis, gangrene is a complication where the diabetes and peripheral angiopathy likely contribute. Peripheral angiopathy hinders blood flow and healing to the area, further increasing the risk of developing gangrene and the worsening of the decubitus ulcer; while the diabetes increases the likelihood of gangrene, as well as infection. Because of this, all the conditions contributing to the principal diagnosis should be included.

By including each of these known contributing factors, we can create a more complete picture of what is happening with the patient and why. Additionally, listing all the conditions responsible for the patient’s visit will help explain the medical necessity for the provider’s plan of care for the patient, which will facilitate payer reimbursement.

Lindsey Bush, BA, MA, CPC, Development Editor, AAPC