Revenue Cycle Insider

Question: A 76-year-old right-handed patient with a history of stroke and left-sided hemiparalysis presented with painful blisters on their left foot. They have type 2 diabetes mellitus, and their spouse was worried the blisters were a diabetic foot complication. The patient has a history of cerebral infarction with residual left hemiparalysis. They wear an ankle-foot orthosis (AFO) on the affected lower leg and foot for ambulation, and the blistering appeared in the area where the AFO and shoe rub against the skin. The provider performed an exam and determined the blisters were caused from friction from the AFO. The documentation does not mention a diabetic foot ulcer or any cause-and-effect relationship between the blisters and the diabetes. Which ICD-10-CM code(s) are appropriate for this encounter?

New Jersey Subscriber

Answer: In the outpatient setting, the blister is listed as the primary diagnosis because it is the reason for the encounter.

If you look to the ICD-10-CM Official Guidelines for Coding and Reporting, Section IV (Outpatient Coding Guidelines), IV.H says: “Code all documented conditions that coexist at the time of the encounter/visit and require or affect patient care treatment or management. Do not code conditions that were previously treated and no longer exist. However, history codes (Z codes) may be used if the historical condition or family history has an impact on current care or influences treatment.”

With that guidance, you’ll need to delve into the documentation to figure out which conditions affected this specific encounter.

The provider documents the blisters as caused by friction from the AFO rather than diabetes, so do not assume a diabetic foot complication. The patient’s stroke history, however, is relevant to the encounter: You can report the residual hemiparalysis as an additional diagnosis because it provides more context and more directly explains the ambulatory impairment that contributed to the blistering. Report diabetes separately only if it is documented as a current condition affecting care or management during the encounter and no diabetic complication is documented.

Based on the documentation provided, the appropriate code sequence is:

• S90.822A (Blister (nonthermal), left foot, initial encounter)
• I69.354 (Hemiplegia and hemiparesis following cerebral infarction affecting left non-dominant side)
• E11.9 (Type 2 diabetes mellitus without complications), but only if the provider noted that the diabetes was evaluated, monitored, or reasonably impacted care — which is often implied in foot-related presentations

While the provider mentioned the spouse’s concerns in the medical record, they did not link the blister to diabetes in the documentation; therefore, you shouldn’t report a diabetic skin/foot complication code, as the provider documented that the blisters were caused by friction from the ambulatory AFO. However, it may make sense to report E11.9 as a coexisting chronic condition because it is clinically relevant to a foot presentation and reasonably influences risk assessment and management, consistent with ICD‑10‑CM Guideline Section IV.H.

Rachel Dorrell, MA, MS, CPC-A, CPPM, Production Editor, AAPC