You’ve probably heard the saying, “A picture is worth a thousand words.” The same logic applies to ICD-10 coding—albeit in a less extreme manner. While you probably won’t need a thousand ICD-10 codes to paint a complete picture of a patient’s diagnosis, there’s a good chance you’ll need more than one—and for many rehab therapists, that represents a huge departure from the coding status quo. With that in mind, here are a few tips for using a multi-code approach to selecting ICD-10 codes:

1. Question the referring physician.

I’m guessing that a hefty portion of your referral scripts contain only a single diagnosis code from the referring physician. And while a plug-and-go protocol—that is, mindlessly transferring the referring physician’s code to your documentation without a second thought—might fly with ICD-9, it won’t work so well with ICD-10. That’s because the new code set places a huge emphasis on clinical judgment (which, incidentally, is why those oh-so-coveted “cheat sheets” could land you in hot water). Why? Well, look at it this way: one of the driving forces behind the transition to ICD-10 is that it allows providers to represent patient diagnoses in a much more detailed, specific way. And who better to identify—and code for—that specificity than an actual specialist?

Remember, your physicians aren’t the musculoskeletal experts; you are. That’s why it’s so important that you take a second look at each referral diagnosis to ensure the physician’s code selection truly represents the patient’s situation in the most accurate, specific, complete way possible. In many cases, you may find it necessary to swap in a more specific primary diagnosis code and/or add secondary codes to express the full breadth of the patient’s reasons for seeking your services. Otherwise, your payers might be left questioning the medical necessity of those services—which could lead to denied payment. And at that point, “But my referring physician said…” will not serve as a valid excuse; you—not your referring doc—will be the one who suffers the financial consequences of poor coding practice.  

2. Account for all affected body parts and lateralities.

If you’ve already started perusing the ICD-10 code set—and at this point in the game, I really hope you have—you may have noticed that many of the “bilateral” codes you’ve come to know and love didn’t make the ICD-10 cut. Instead, in most cases, you’ll see separate code options for both left and right. So, if a patient is experiencing a particular condition on both sides of his or her body, it would make sense to submit both of those codes—and that is exactly what you are supposed to do. But this tweak to your coding code of conduct (say that five times fast!) isn’t the product of some evil ploy to make you submit more codes; rather, it’s a mechanism for collecting more detailed data (i.e., tracking the total number of instances of a particular diagnosis on the left as well as the total number of instances on the right).

That said, ICD-10 often does provide “multiple sites” codes for single conditions involving multiple sites (e.g., osteoarthritis). When no such code is available, though, you’ll need to submit separate codes for each affected body part.

3. Use external cause codes when appropriate.

As Courtney Lefferts explains in this blog post, the group of diagnosis codes you submit for any one patient should answer the following questions as completely and accurately as possible:

  • Who?
  • What?
  • Where?
  • When?
  • Why?

To answer some of those questions, you’ll need to submit external cause codes. Found in Chapter 20 of the ICD-10 code set, external cause codes provide additional context around certain diagnoses. It’s important to note, however, that you can’t submit external cause codes for all principal diagnosis codes; external causes only apply to certain categories of codes, as noted within the coding guidelines that accompany each chapter of the code set. Most of the external cause code-eligible diagnoses that are relevant to rehab therapists appear in Chapter 19, also known as the injury chapter. Each external cause code answers one of four questions:

  • How did the injury or condition happen?
  • Where did it happen?
  • What was the patient doing when it happened?
  • Was it intentional or unintentional?

Even though there is no national requirement to use external cause codes, if you have the clinical information necessary to select one or more of these supplementary codes—and the patient’s primary diagnosis code allows for the submission of those codes—then you absolutely should do so. For a more in-depth look at the ins and outs of external cause codes, check out this blog post and this video.

4. Order codes according to significance.

When it comes to submitting multiple diagnosis codes on a single claim, order matters. That’s because, while the HCFA 1500 forms were updated in 2013 to accommodate ICD-10, they only allow for four diagnosis code pointers per line item. Thus, it’s important that you’ve arranged the ICD-10 codes in order of importance, with the primary code appearing at the top, followed by the codes that most strongly support the medical necessity of your services. That way, you’ll be able to point those diagnoses to the CPT codes appearing on the claim.

5. Don’t submit more codes for the sake of submitting more codes.

Sure, ICD-10 likely will increase the average number of codes you’re submitting for each patient. But, that doesn’t mean you should approach coding with the goal of selecting as many codes as possible—relevance be damned! Instead, submit as many codes as necessary to describe the patient’s condition as best you can—whether that’s one code or 21. However, keep in mind that, as noted above, each claim form can only accommodate up to 12 codes.


While a picture might be worth a thousand words, a good coder will express those words in the most efficient way possible. In many cases though, a single ICD-10 code won’t suffice. So, to avoid creating half-developed snapshots of your patients, focus on using multiple codes to capture their diagnoses clearly and completely.