Podiatry Coding & Billing Alert

A how-to guide on successfully coding DFUs under ICD-10

Diabetes and diabetic wounds are on a rapid, linear growth with no signs of plateauing, making early diagnosis and treatment essential. In order to prevent denials, you need to ace ICD-10 coding for these conditions.

A 2014 CDC report estimates that 29.1 million people in America (9.3 percent of the population) have diabetes, and it’s the leading cause of non-traumatic lower-limb amputations. A patient will lose a limb in the U.S. due to diabetes every five minutes. The severity of the epidemic and the expected increase in diabetic foot ulcers (DFUs) make familiarity with their coding crucial.

Determine the DFU Code First, but Code it Last

The L97-series is the DFU series, and in ICD-10 you code any ulcer on a diabetic patient’s foot as a DFU, even if pressure or arterial disease played a role. The fourth character in these codes represents where the ulcer is located on the foot, while the fifth-character options for DFU codes relate to which foot:

Coding note: In ICD-10, “and” truly means “and/or.” You can code L97.4xx without the presence of two ulcers, one on both the heel and the midfoot.

• L97.4 — Non-pressure chronic ulcer of heel and midfoot 

          o 0 – Unspecified heel and midfoot
          o 1 – Right heel and midfoot
          o 2 – Left heel and midfoot

• L97.5 — Non-pressure chronic ulcer of other part of foot

          o 0 – Unspecified foot
          o 1 – Right foot
          o 2 – Left foot

For example, L97.42- (Non-pressure chronic ulcer of left heel and midfoot).

The Sixth Character Indicates Severity

DFU codes use the sixth character to describe the ulcer’s severity. You may notice that characters 1 and 2 refer to the depth of the ulcer while 3 and 4 describe the depth of the ulcer’s necrotic tissue. The APMA has addressed this discrepancy with the World Health Organization, as a wound’s depth doesn’t necessitate necrosis, but as of this publication date no changes have been made.

• 1 – Limited to breakdown of skin
• 2 – With fat layer exposed
• 3 – With necrosis of muscle
• 4 – With necrosis of bone
• 9 – With unspecified severity

Coding note: The “unspecified” options indicate to the payer that the documentation was incomplete and may lead to denial of payment.

“Code First” Caveat Complicates Things

DFU codes all have the “code first” disclaimer attached: “Code first any associated underlying condition, such as diabetic ulcers (E08.621, E08.622, E09.621, E09.622, E10.621, E10.622, E11.621, E11.622, E13.621, E13.622).” 

“Code first” indicates that an additional code is required and you should list this first. The order you use matters, so always code the diabetes code first (E10.621, Type 1 diabetes mellitus with foot ulcer or E11.621, Type 2 diabetes mellitus with foot ulcer) and then the L97 code on the claim form. 

First, Code the Underlying Condition (Diabetes Mellitus)

• E10.621 

          o Use additional code to identify site of ulcer (L97.4-, L97.5-)

• E10.622 — Type 1 diabetes mellitus with other skin ulcer 

          o Use additional code to identify site of ulcer (L97.1-L97.9, L98.41-L98.49)

In one of the surprisingly convenient changes in ICD-10, by substituting E11 for E10 in any of the above codes you code for Type 2 diabetes:

• E11.621 

          o Use additional code to identify site of ulcer (L97.4-, L97.5-)

• E11.622 — Type 2 diabetes mellitus with other skin ulcer

          o Use additional code to identify site of ulcer (L97.1-L97.9, L98.41-L98.49)

You’ll note that ICD-10 prompts you to add a second code that represents the anatomic location (right heel, left heel, etc.) as well as severity of the ulcer denoted by exposed tissue depth or layers, for example:

• E11.621
• L97.423 — Non-pressure chronic ulcer of left heel and midfoot with necrosis of muscle.

“Use Additional Code” Complicates Things Further

Just as the order matters when we see “code first,” the order in which the codes are listed is important when one is instructed to “use additional code.” Under E11.621, we see the directions to “Use additional code to identify any insulin use (Z79.4)” and “Use additional code to identify oral hypoglycemic use (Z79.84).” You must also code Z79.4 if the patient uses insulin and Z79.84 if the patient is using an oral hypoglycemic.

So, list Z79.4 and Z79.84 codes after E11.621. You code the diabetes code first, then the insulin/hypoglycemic next, and finally the ulcer.

Let’s Put it All Together

Let’s go through the coding of a typical patient with type 2 diabetes who uses an oral glycemic and has a chronic right lateral midfoot ulcer with necrosis of a muscle. When coding this patient encounter, you would start with L97.4—because this ulcer is on the midfoot. The fifth character would be 1 because it is the right foot and the sixth character would be 4 because there is necrosis of bone. That leaves us with L97.414 (Non-pressure chronic ulcer of right heel and midfoot with necrosis of bone), which carries the instruction to “code first” E11.621.

Since this patient uses an oral hypoglycemic, the E11.621 “use additional code” requirement necessitates the Z79.84 code. Following the rules of “code first” and “use additional code,” the proper coding order on your claims form would be: E11.621 first, Z79.84 second and L97.414 last.