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ICD-10-CM & Wound Care Coding: Essential Tips for Today's Practice

Healthcare providers are expected to conduct accurate coding under ICD-10. This article offers practical guidance to the diagnostic coding for ulcers and wounds, as well as insights on adding 5th, 6th, and 7th characters to coding.


It is nearly one year since the expiration of the “grace period” set forth by the Centers for Medicare and Medicaid Services (CMS) for ICD-10-CM. Today, it’s more important than ever for wound care providers to ensure they’re coding to the highest specificity and following all ICD-10 guidelines. While it is still unclear exactly how forgiving CMS was under this grace period, it is possible that some things that were working in the first year of ICD-10 may not continue to be satisfactory. Let’s look specifically at proper diagnostic coding when it comes to wound care.


There have been disagreements, debates, and articles written on the difference between what’s considered to be a “wound” versus an “ulcer.” Sometimes, ICD-10 is almost like its own language, and this is one of those situations. Be aware that in ICD-10 language, a wound is something that occurs traumatically. All wound codes start with the letter “S,” placing them in Chapter 19 of the tabular index “Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88).” The term “ulcer” refers to a break in the skin that fails to heal as it should and is typically more chronic in nature. While many clinicians may interchange the terms “ulcer” and “wound” as if they are synonyms, they are not synonyms when it comes to ICD-10 coding.


Once an ulcer has been identified, the clinician must determine the ulcer type in order to use the correct code. Options include diabetic foot ulcer (DFU), pressure ulcer, stasis ulcer, or arterial ulcer. DFU coding begins with the
“L97-” codes. (Note that throughout this article, the “-” at the end of any code stem indicates that more characters are required to complete the code.) Pressure ulcer codes begin with
“L89-”; stasis ulcer codes begin with “I83-”; and codes for arterial ulcers are in the “I70-” section. Clinicians may wonder what to do when a DFU is also related to pressure. For example, a patient who lives with diabetes, peripheral arterial disease, and neuropathy may develop an ulcer on the dorsal proximal interphalangeal joint of a contracted second toe. This could be considered to be an arterial ulcer, a neuropathic ulcer, or a pressure ulcer. The National Pressure Ulcer Advisory Panel provides us with guidance in this area. For ICD-10 purposes, if there is an ulcer on the foot of a diabetic patient, consider it a DFU (and code using “L97-”). This is true even if arterial disease and/or pressure has played a role in its development.


Looking more closely at the “L97-” code options for DFUs, we see that we have to choose a 4th character of either “4” or “5,” with the options being “L97.4-” (non-pressure chronic ulcer of heel and midfoot) or “L97.5-” (non-pressure chronic ulcer of other part of foot). The word “and” being in the description of the “L97.4-” codes brings us to an important ICD-10 lesson and another example of it sometimes being its own language. Whenever the word “and” appears in ICD-10 code descriptions, it actually means “and/or.” Therefore, it is not necessarily implied when using an “L97.4-” code that the patient has two ulcers present (one involving the heel and one involving the midfoot). Once the 4th character is determined, a 5th character is required. The 5th character options are:

For “L97.4-”         

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

For “L97.5-”

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

A 6th character is required for these codes as well, and those options are listed here: 

For “L97.4-” and “L97.5-”

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

Notice the “unspecified” options, which indicate to the payer that the documentation was incomplete and may lead to denial of payment. One should almost always avoid these options. With the 5th character laterality options, for example, a selection of “0” would indicate that the documentation specified neither left nor right. Notice in the 6th character options that “1” and “2” reference the depth of the ulcer, but “3” and “4” reference the depth of tissue that is necrotic. Just because an ulcer extends to a certain depth does not necessarily mean there is necrosis of tissue to that depth. Multiple organizations, including the American Podiatric Medical Association and the Alliance of Wound Care Stakeholders, have submitted requests to the World Health Organization to make changes to the code descriptions that would address this inconsistency, but no changes have occurred as of press time. 

Coding of a DFU is not complete after choosing the 4th, 5th, and 6th characters because the “L97-” codes require one to “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).” Of these options, the most commonly used codes for DFUs are “E10.621” (type 1 diabetes mellitus with foot ulcer) and “E11.621”  (type 2 diabetes mellitus with foot ulcer). “Code first” indicates that an additional code is required and should be listed first. Therefore, the order matters and “E10.621” or “E11.621” should precede the
“L97-” code on the claim form. For a patient living with type 2 diabetes and a foot ulcer, we may still not be finished, because 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).” Therefore, we must also code “Z79.4” if the patient uses insulin and “Z79.84” if the patient is using oral hypoglycemic(s). 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.” List the “Z79.4” or “Z79.84” code after “E11.621.” If this is not a question that’s been posed to those patients living with type 2 diabetes, clinicians may be surprised to learn how many of them are now taking insulin in comparison to 10 years ago.

Next, let’s go through the coding of a typical type 2 diabetes patient who is taking daily insulin and has a chronic left lateral midfoot ulcer with necrosis of a muscle. When coding this patient encounter, start with “L97.4-” because this ulcer is on the midfoot. The 5th character would be “2” because it is the left foot, and the 6th character would be “3” because there is necrosis of muscle. That leaves us with “L97.423,” which carries the instruction to “code first E11.621.” Since this patient uses daily insulin, “Z79.4” is necessary as well. The order of these codes would be “E11.621”; “Z79.4”; and “L97.423” when following the rules of “code first” and “use additional code.” 


When coding a pressure ulcer, look to the “L89-” codes:

Pressure Ulcer Podiatry Codes

L89.51- Pressure ulcer of right ankle
L89.52- Pressure ulcer of left ankle
L89.61- Pressure ulcer of right heel
L89.62- Pressure ulcer of left heel
L89.89- Pressure ulcer of other site

Do not confuse “other” and “unspecified.” For reasons stated already, it is normally best to avoid  “unspecified” codes, but the use of  “other” codes is fine when appropriate. Select the “other” option when the documentation does specify the location of the ulcer but there is not a more specific code that exists. An example of when this would be appropriate is a pressure ulcer on a toe. This would not fall under the codes for ankle or heel. Therefore, in this situation, consider the toe an “other” site. All of these codes require a 6th character: 

6th Character Coding Options For Pressure Ulcers:

0 – Unstageable
1 – Stage I
2 – Stage II
3 – Stage III
4 – Stage IV
9 – Unspecified stage

Use the “unstageable” option when the deepest layer of tissue involved cannot be determined because it is covered by slough and/or eschar, and it is not possible to stage the ulcer. These codes are easier to complete than the DFU codes, as they do not have any “use additional code” instruction and the only “code first” instruction is to “code first any associated gangrene (I96).” This does not need to be included if there is no associated gangrene. Stasis ulcer coding begins with either “I83.0-” (varicose veins of lower extremities with ulcer) or “I83.2-” (varicose veins of lower extremities with both ulcer and inflammation). Both of these require a 5th character: 

5th Character Coding Options For “I83.0-” and “I83.2-”

0 – Unspecified lower extremity
1 – Right lower extremity
2 – Left lower extremity

Once again, attempt to avoid the  “unspecified” option. If a patient has ulcers involving the right and left extremities, list both codes, as there is no “bilateral” option. After selecting the 5th character, a 6th character is required for these codes: 

6th Character Coding Options For “I83.0-” and “I83.2-”

1 – With ulcer of thigh
2 – With ulcer of calf
3 – With ulcer of ankle
4 – With ulcer of heel and midfoot
5 – With ulcer, other part of foot
8 – With ulcer, other part of lower leg
9 – With ulcer of unspecified site

When looking at the 6th character option of “4,” remember that “and” actually means “and/or.” All of these “I83.0-” and “I83.2-” codes carry the instruction to “use additional code to identify severity of ulcer (L97-).” This brings us back to the “L97-” codes already discussed. Remember, with the “use additional code” instruction the “L97-” code will come after the “I83-” code when sequencing these codes. The final ulcer option is arterial ulcers, and these should be coded starting either with “I70.23-” (atherosclerosis of native arteries of right leg with ulceration) or “I70.24-” (atherosclerosis of native arteries of left leg with ulceration). These codes require a 6th character (options are the same as those listed for stasis ulcers). Also, similar to coding for stasis ulcers, with these arterial ulcer codes one must “use additional code to identify severity of ulcer (L97-).” If arterial ulcers are present on both right and left lower extremities, list both codes.


Character Options For Wound Care Coding:

Moving away from what ICD-10 considers to be ulcers and focusing on wounds, let’s look at codes for the pathologies most commonly encountered for podiatry. The codes that start with “S91.0-” are the codes for open wounds of the ankle. Codes for open wounds of toes without damage to the nail begin with “S91.1-” and codes for open wounds of toes with nail damage start with “S91.2-.” For an open wound of the foot, codes start with “S91.3-.” These codes all require a 5th character: 

5th Character Coding Options For “S91-”

0 – Unspecified open wound
1 – Laceration without foreign body
2 – Laceration with foreign body
3 – Puncture wound without foreign body
4 – Puncture wound with foreign body
5 – Open bite

All of these codes also require a 6th character. The 6th character options for the “S91.0-” codes are “1” for right ankle and “2” for left ankle. The 6th character options for the “S91.1-” and “S91.2-” codes are more extensive:

6th Character Coding Options For “S91.1-” and “S91.2-”

1 – Right great toe
2 – Left great toe
3 – Unspecified great toe
4 – Right lesser toe(s)
5 – Left lesser toe(s)
6 – Unspecified lesser toe(s)
9 – Unspecified toe(s)

The 6th character options for the “S91.3-” codes are “1” for right foot and “2” for left foot. When looking at these options, remember the recommendation to avoid the “unspecified” codes. Finally, all of the “S-” codes listed in this article require a 7th character. This is a point of confusion among many, mostly owing to misleading descriptions of these characters. The 7th character options are “A,” “D,” and “S.” Use “A” if active care was provided during that visit. Use “D” if the care provided can be considered follow-up care. The selection of “A” or “D” has nothing to do with whether the patient has seen this doctor in the past or whether it is the first time the patient presented for this problem. The ICD-10 descriptions of “A” being for an “initial encounter” and “D” being for a “subsequent encounter” are misleading because they actually have nothing to do with whether it is an initial or subsequent encounter between that doctor and that patient, as those terms are most frequently interpreted. Base the selection solely on the type of care provided. 

Jeffrey D. Lehrman is on the coding committee for the American Podiatric Medical Association, serves as an expert panelist on, and is a fellow of the American Academy of Podiatric Practice Management. Follow him on Twitter @DrLehrman.


1. National Database of Nursing Quality Indicators: Pressure Ulcers and Staging. Accessed online: 

2. American Podiatric Medical Association: Coding Resource Center. Accessed online: 

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Jeffrey D. Lehrman, DPM, FASPS, MAPWCA
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