Updated on: March 14, 2016

ICD-10: Initial Versus Subsequent Encounters for the Chiropractor

Original story posted on: March 30, 2015

Chapter 19 of the ICD-10 code set covers injury, poisoning, and certain other consequences of external causes.

While chiropractic physicians will primarily use the chronic and recurrent musculoskeletal conditions from Chapter 13, Diseases of the Musculoskeletal System and Connective Tissue, there are several relevant codes from Chapter 19. They include acute musculoskeletal conditions such as sprains and strains of the spine, codes that will be used frequently by chiropractors. They are easily identifiable because they begin with the letter “S.” These codes require the addition of a seventh-character extension that specifies the episode of care or encounter.


The three choices for most of the “S” codes that will be used by chiropractors are:

A: Initial encounter

D: Subsequent encounter

S: Sequela

The official guidelines (with a few changes for 2014) indicate the following:

Seventh character “A,” initial encounter, is used while the patient is receiving active treatment for a condition. Examples of active treatment are surgical treatment, emergency department encounters, and evaluation and continuing treatment by the same or a different physician.

Seventh character “D,” subsequent encounter, is used for encounters after the patient has received active treatment of a condition and is receiving routine care for the condition during the healing or recovery phase. Examples of subsequent care are cast change or removal, an X-ray to check healing status of fracture, removal of external or internal fixation device, medication adjustment, other aftercare, and follow-up visits following treatment of the injury or condition.

Seventh character “S,” sequela, is for use for complications or conditions that arise as a direct result of a condition, such as scar formation after a burn. The scars are sequelae of the burn. When using seventh character “S,” it is necessary to use both the injury code that precipitated the sequela and the code for the sequela itself. The “S” is added only to the injury code, not the sequela code. The seventh character “S” identifies the injury responsible for the sequela. The specific type of sequela (e.g. scar) is sequenced first, followed by the injury code.

If applied to an acute injury that is typically treated in a medical setting, such as an abrasion to the right lower leg, the application of these characters makes sense. The ICD-10 code for this condition is S80.811_. The underscore indicates that this code requires a seventh character, and the instructions within the tabular list provide the options of A, D, or S.

While the patient is undergoing active treatment for this abrasion, the correct code would be S80.811A to indicate “initial encounter.” This does not mean the same thing as “initial visit;” rather, it explains that the patient is undergoing active treatment, such as debridement of the wound. When this patient returns a week later for aftercare to check on the status of the wound, the code would change to S80.811D for “subsequent encounter.”

If the patient suffered some complication as a result of the abrasion, but the abrasion is no longer in need of treatment, then the code would be S80.811S. In this case, the injury code (S80.811S) is listed second and the complication is coded first. The case appears to be tidy and relatively straightforward. An injury began in active treatment, progressed through the healing phase, and suffered a late effect. 

While this seems logical, it is more difficult to apply these seventh-character extensions to chiropractic or ongoing therapies. “A” indicates “initial encounter,” but it may be more clearly described as “active treatment” as outlined in the official guidelines. This poses the question: at what point is the patient no longer receiving “active treatment?” For example, suppose a patient presents with S16.1xxA, strain of muscles, fascia, and tendon at neck level, initial encounter. The code set does not define a point in time when it would be appropriate to begin using the “D” as the seventh character. Rather, it tells us that this would be appropriate once the patient has entered the “healing or recovery phase of care” or once the patient is in “aftercare or follow-up.” The clinician must decide when this transition occurs. It might be two days, two weeks, or two months after care begins. 

The concern stems from the fact that there is generally no reimbursement to chiropractors for care that occurs after the patient no longer is progressing. And this may be synonymous with the use of the “D.” Payers have not yet provided guidance or clarification on this matter. However, drafts of Medicare local coverage determinations provide some insight. Though not official yet, they provide lists of diagnosis codes that Medicare is expected to allow chiropractors to use. Unfortunately, some jurisdictions list “S” codes that end only in “A,” which implies that chiropractors will only be reimbursed while the patient is in “active treatment.” Other jurisdictions list “S” codes that end with “A” and “S” but noticeably omit the “D.” Again, this suggests that care during the “healing or recovery” phase may not be reimbursable. However, at least one Medicare Administrative Contractor lists all three seventh character extensions: the “A,” the “D,” and the “S.” Therefore it is unclear what Medicare may do with these codes on Oct. 1, 2015. Third-party payers, who are likely to follow Medicare’s lead, will also need to provide clarification. 

While it could go any number of ways, at this time it may be prudent for chiropractic physicians to use the “A” with injury codes for as long as they deem the patient to be receiving “active treatment” (that is, as long as the patient continues to progress). When the patient ceases to progress, but the provider wishes to continue treatment to facilitate healing, then the “D” should be applied. Payors may not reimburse when the “D” is used, and providers should have that conversation with their patients to make them aware that they may need to pay out of pocket for these services. 

One other consideration is the use of the “S” for “sequela.” Since this would be used to describe a condition that has resolved, or at least is no longer being treated, it may lead third parties to deny care based on liability. For example, if a patient presents with M50.32, other cervical disc degeneration, mid-cervical region, and the provider determines that it is a direct result of a previous neck strain that is no longer present, it could be coded as M50.32 followed by S16.1xxS (which identifies the strain as the cause of the degeneration, which is the condition that is being treated).

The third party could deny payment based on the fact that some other payer may be liable for the accident thatcaused the neck strain in the first place. 


Disclaimer: Every reasonable effort was made to ensure the accuracy of this information at the time it was published. However, due to the nature of industry changes over time we cannot guarantee its validity after the year it was published.

Evan M. Gwilliam, DC, MBA, BS, CPC, CCPC, CCCPC, NCICS, CPC-I MCS-P, CPMA, executive vice president of ChiroCode and Find-A-Code LLC, graduated from Palmer College of Chiropractic as valedictorian and is a certified professional coding instructor, medical compliance specialist, and professional medical auditor, among other things. He provides expert witness reports, medical record audits, consulting, and online courses for healthcare providers. He also writes books and articles for trade journals and is a sought-after seminar speaker. He has a bachelor’s degree in accounting and a master’s of business administration, and he is one of the few clinicians who is a certified ICD-10 Instructor and certified MACRA/MIPS healthcare professional.