Chiropractic Coding Confusion With ICD-10 Injury Codes

Despite the dust settling over ICD-10, there is still a significant amount of chiropractic coding confusion in respect to utilizing the injury codes — specifically  7th digit character extenders A, D or S. While there appear to be some differing options on how to use these extenders, I’d like to offer some perspectives to help clear the mud and enable you to move forward and confidently use these coding options.

Context is Key

One of the first things chiropractors (and chiropractic billing staff) need to remember is that none of these ICD-10 codes was created for us. In fact, we tend to look at ICD-10 coding through the lens of musculoskeletal coding because, naturally, that is the vast majority of what we deal with. But in respect to the 7th digit character extenders, this can actually muddy the waters even further. Here’s why:

We need to keep in mind that the 7th digit character extender codes appear in the INJURY and POISONING section of the ICD-10 codeset. As chiropractors, our first instinct is to latch on to the injury portion and ignore the poisoning part. And here’s where things can go awry because the phases of treatment of a musculoskeletal injury such as a sprain or a strain is actually quite different than the phases of treatment applied to a poisoning injury – even though both of these diagnoses can end up using the 7th digit character extender.

Naming Nonsense

The situation is further magnified by the fact that the 7th Digit Character Extenders are poorly named in my opinion. Let’s start with the “Extender” part. The stupidity of this segment of the name seems to imply that you can simply add an A, D or S to any code to “extend” it. This is completely incorrect. ICD-10 coding is not a creative art and you don’t add A, D or S to codes that don’t require it. Instead, the 7th digit character extender is an option you must choose for certain codes within the Injury or Poisoning section to indicate the status of the treatment for which you are applying the diagnosis. But unfortunately, the naming nonsense doesn’t stop there.

The “A” for Initial Treatment appears to indicate that you use the “A” extension for only the first visit. Alas – this is also WRONG! Worse, this is further befuddled by the fact that the “S” extension is labeled as “Subsequent Visit.”

In my opinion, most of the confusion on the A, D or S has been magnified by some well-intentioned folks who simply didn’t read ICD-10-CM guidelines.  Here’s why:

The Chiropractic Application of A, D and S

In chiropractic terms, the 7 digit character extender “A” should be applied for all episodes of “active treatment” of that diagnosed injury (again, provided the ICD-10 code requires a seventh digit). In other words, if your diagnosis is a cervical sprain (S13.4XXA) you will use that “A” character for the first, second, third and twenty-third visit (if necessary)…so long as active care is still being rendered.

Some more confusion tries to slip in when chiropractors begin to utilize other therapies such as massage or rehab. But we need to keep in mind that the 7th digit character extender is not dependent on the type of therapy you are doing; it’s describing upon the PHASE of the condition.

Going back to our example of S13.4XXA (cervical sprain) and applying this logic, there’s no need to change your coding by introducing massage, physical therapy, modalities or any other intervention that you employ during the ACTIVE phase. The code remains S13.4XXA.

What About the Subsequent Care?

“What about the “D” then?” you ask. Good question. ICD-10-CM defines subsequent encounters (which get the “D” 7 digit character extender) as “encounters after the patient has received active treatment of the injury and is receiving routine care for the injury during the healing or recovery phase.”

In chiropractic, we use another name for that “routine” care phase which follows our active treatment of the problem; we call it “maintenance” care. So this routine/maintenance care is the “subsequent” care that is rendered after the active condition/injury is resolved. And it’s purpose is to maintain the progress that you’ve made. When you reach this phase, you apply the “D” to signify the “subsequent” visit. And, unfortunately, expect a D for denial back from the payer (since it’s maintenance).

The other possible application of the “D” character extender is for second-opinion or IME situations. In these cases, the examiner is not actually participating in the active care and the evaluation for IME purposes is “subsequent” to the active care. Most payers have not offered any thoughts to this application; so, if they object and insist on you giving your second opinion with an “A” also, you might want to defer to their understanding as they are the ones signing your checks.

Coding for Sequela

The seventh character “S” is meant “for use for complications or conditions that arise as a direct result of an injury, such as a scar formation after a burn. The scars are sequelae of the burn. In other words, sequel are the late effects of an injury.”

While it is possible that there are residual or late effects of a musculoskeletal injury that painfully manifest themselves after active treatment is completed, such a diagnosis typically produces a “pre-existing” condition denial and therefore, chiropractors should apply the “S” character extender with caution.

Why The 7th Digit Makes Sense (Almost)

If this all sounds horribly confusing, it’s because of our musculoskeletal perspective that I mentioned above. If you were to look at things from the lens of how a poisoning (and other non-musculoskeletal injuries) are treated, the 7 Digit almost makes sense because the treatment of many of these injuries will typically will have three separate and easily distinguishable phases.

For example: let’s say the patient accidentally drank some toxic substance that immediately caused him to become extremely ill. When the patient first enters the hospital for poisoning, the treating doctors would apply a diagnosis from the poisoning codes that would end in the seventh character “A.” And whether the hospital visit included observation, medication, imaging and/or a gastric lavage, those encounters would all be related to the active treatment of that poisoning and get a “A.”

Hopefully, the hospital would be able to successfully treat the poisoning and likely, they would release the patient to a specialist or their primary care provider for follow-up care. This treatment would be different than what was rendered in the emergency room and may consist of lab tests, physical examinations, monitoring, dietary modifications or whatever the doctor determined was necessary to promote a successful resolution of the healing or recovery phase. And these visits would get a D character for subsequent visits.

Finally, depending on the substance ingested, it’s quite possible that the patient may have some residual effects that last for some time. And these effects may warrant additional treatment down the line. This treatment may also be different than what was applied in the first two phases of care. Yes, if you are following correctly, this treatment would then get the “S” character for sequela.

Medicare & the American Academy of Professional Coders

As you can see, the treatment of the musculoskeletal injury that would enter our chiropractic offices is significantly different than the treatment of a poisoning — yet, they both can potentially utilize the 7th digit character extender. But, as I explained above, for our purposes as chiropractors, the “A” is going to be utilized the vast majority of circumstances for us.

Because I know that there are differing opinions on this, let me also point out the opinions of the two big hitters in the coding world: Medicare (who makes a ton of the rules and policies that everyone else follows) and AAPC (who is the single largest entity of professional coders who interpret those rules).

At this point in time in Medicare, it is interesting to note that most Medicare payers have only approved injury codes with the “A” extension for chiropractors. That should say a lot about how to apply your 7th digit character extender coding right there — for Medicare and non-medicare payers (who generally follow Medicare’s rules anyway). Check under the Local Coverage Determinations (LCD’s) for your Medicare carrier for specific codes that are approved.

Furthermore, the AAPC supports the same logic and rationale that I explained above for coding the 7th digit character extender. In fact, much of the terminology used above is from AAPC publications, their ICD-10 online course and articles such as this and this.

What You “Think” You Heard In Chiropractic Seminars

Finally, just because you “think” you heard to do the 7th Digit Character Extender coding one way, doesn’t mean you actually heard it correctly. We’ve had a ton of emails from folks who attended other chiropractic seminars and took ICD-10 courses from reputable instructors (including myself) and STILL got it wrong. Yes, I’ve had several seminar attendees misquote me and other chiropractic speakers. So just in case you didn’t hear it correctly, look at the SAME explanations below:

  • “The A extension for cervical sprain would be used for all visits when the patient is under active care.” — HJ Ross Company blog April 14, 2015   
  •  “The character ‘D’ is not used to report the second visit after the initial treatment of an injury”American Chiropractic Association Facts About the 7th Digit Character Extender
  • The “A” indicates “initial encounter” but it may be more clearly described as to the “Active Treatment” as outlined in the official guidelines. – ChiroCodeInitial Versus Subsequent Encounters for the Chiropractor

Next Steps: Keep It Simple

My final recommendations have not changed after ICD-10 from what I taught in my chiropractic seminars before the transition in October: keep it simple.

Here’s how to do that:

  1. Use the “A” extension on injury codes that require a 7th digit character extender for which you are providing active care (this will be 99% of your cases).


  1. If a payer requires that you submit a code with a “D” or “S” extension because they have a different understanding of the code usage, defer to their perspective. But make them the exception rather than the rule for all your payers.


  1. Keep your ears and eyes open for changes. That means read chiropractic blogs like this one, read your payer newsletters or updates, and attend chiropractic billing seminars. It’s possible that payers will clarify or update their perspective over time and you will need to change. Which is yet another reason to keep it simple, so that your procedures aren’t so convoluted they can’t change with you.