Peripheral vascular disease (PVD), also commonly known as peripheral artery disease (PAD), is a generic term for any progressive disease affecting the noncardiac circulation.  PVD can have various causes, including narrowing (stenosis), occlusion, or spasm.  The underlying cause of PVD can vary and may include diabetes, hypertension, arteriosclerosis, or atherosclerosis.  Coding for PVD is not nearly as simple as it may initially seem, as it may require additional detective work to piece together the patient’s clinical picture.

Arteriosclerosis vs. Atherosclerosis

The arteries are flexible, elastic vessels that carry oxygen to the body’s tissues.  The arteries can harden and lose their elasticity, a condition called arteriosclerosis. Atherosclerosis is a specific type of arteriosclerosis caused by the accumulation of fats, cholesterol, and other substances within the arteries.  This build-up is referred to as plaque.  Peripheral atherosclerosis is most common in the lower extremities and its progression can lead to loss of oxygen to the body’s tissues, resulting in pain, ulceration, and tissue death (gangrene).

The Hierarchy of Arteriosclerosis

The ICD-10-CM classifies both arteriosclerosis and atherosclerosis to category I70, Atherosclerosis.  The codes in this category are based on the specific artery(ies) affected and whether bypass grafts or the native circulation are involved.  Subcategory I70.2 is used to report atherosclerosis of the extremities with varying levels of progression from intermittent claudication (pain induced by exercise and relieved by rest) to rest pain to ulceration and ultimately to gangrene.

Codes in category I70 are assigned based on this hierarchical structure; when multiple manifestations are present, only one code from I70 is assigned.  For example, a patient presenting with arteriosclerosis with intermittent claudication and rest pain is only assigned code I70.229, Atherosclerosis of native arteries of extremities with rest pain, unspecified extremity.  The index pathway for this is as follows:

Note the subterm “with” listed below the subterm for arteriosclerosis of the extremities.  Guideline I.A.15. tells us that conditions listed under “with” have an assumed causal relationship.  That means that when a person presents with arteriosclerosis and an ulcer, the conditions are linked unless the provider documents another cause for the ulcer (e.g., pressure injury).  It is also important to note that the index entry shown here is incomplete and there are additional subterms for laterality, which provide further specificity in coding.

But Wait… There’s More!

This may seem like a lot to unpack just to simply assign a single code identifying the patient’s arteriosclerosis.  The complexity of coding this condition is compounded if the patient has diabetes or an ulcer.

The ICD-10-CM coding system assumes a causal relationship between diabetes and peripheral angiopathy, based on the “with” convention noted previously.  Angiopathy means vascular disease, therefore peripheral angiopathy is the same thing as peripheral vascular disease and since arteriosclerosis is a type of PVD, there is an assumed relationship between diabetes and arteriosclerosis.  This concept was immortalized in Coding Clinic for ICD-10-CM/PCS, Second Quarter 2018: Page 7.  If the patient in the example above also has type 2 diabetes, this is reported first with code E11.51, Type 2 diabetes mellitus with diabetic peripheral angiopathy without gangrene, followed by code I70.229.

The codes for arteriosclerosis with ulcer have a “Use additional code” note to report an additional code from category L97, Non-pressure chronic ulcer of lower limb, not elsewhere classified, to report the location and depth of the ulcer.  Again, the causal relationship between the ulcer and the arteriosclerosis is assumed unless another cause for the ulcer, such as a pressure injury, is documented.

Putting on Your Detective Hat

Unfortunately, coding arteriosclerosis isn’t as simple as coding from a diagnostic statement in a single report in a medical record.  In cases where the patient has a vascular procedure for the PVD, there is often very specific documentation in the findings of the procedure report.  However, the patient’s pertinent medical history, such as a history of diabetes, is not always documented in the procedure report and may be found in the H&P or other provider progress notes.  The skill of coding arteriosclerosis and its interlaced conditions lies in understanding the disease process, codebook conventions, coding guidelines, and Coding Clinic advice.

Tune in June 17, 2021 for the webinar, “Do Your ICD-10-CM Codes Tell the Patient’s Story?” to learn more about commonly miscoded combination codes, including hypertension, urinary conditions, more about diabetes, ulcers, and arteriosclerosis, and more!

References

American Hospital Association. “Diabetes with Peripheral Angiopathy.” Coding Clinic for ICD-10-CM/PCS, 6 June 2018, p. 7.

“Arteriosclerosis / Atherosclerosis.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 16 Mar. 2021, www.mayoclinic.org/diseases-conditions/arteriosclerosis-atherosclerosis/symptoms-causes/syc-20350569.

Centers for Medicare and Medicaid Services (CMS) and National Center for Health Statistics (NCHS). “ICD-10-CM Official Guidelines for Coding and Reporting, FY 2021 – UPDATED January 1, 2021.”