Q: I was confused when reviewing the strain-sprain coding in ICD-10 – what is the proper use of the A, D and S extensions? Do I use the A extension for the first visit, and the D extension for the second and subsequent visits?
- S13.4XXA: sprain of cervical spine, initial encounter
- S13.4XXD: sprain of cervical spine, subsequent encounter
- S13.4XXS: sprain of cervical spine, sequelae
- S16.1XXA: strain of cervical spine, initial encounter
- S16.1XXD: strain of cervical spine, subsequent encounter
- S16.1XXS: strain of cervical spine, sequelae
At first glance, it may appear obvious and logical when you identify the coding in this format that the initial encounter is for the first visit and the subsequent encounter is for the second and "subsequent" visits. However, that assumption is incorrect; without a full understanding of the definitions of the A and D extensions, it may lead to improper coding (hence your confusion and question on the use of the proper extension).
The term initial encounter is somewhat misleading, as it actually refers to the period of time when the patient is receiving active treatment for the condition. Chiropractic treatment (physical medicine services, etc.) is considered active treatment, as there is "active care" for the condition. Therefore, the A extension S13.4XXA for cervical sprain and S16.1XXA are the codes to use for all visits when the patient is under active care.
Subsequent encounter is the visit(s) after the active phase of treatment. For instance, a medical provider refers a patient to a chiropractor for care; once care is completed with the chiropractor and the patient is being "checked" out by the medical provider, that constitutes the subsequent encounter.
The source of these definitions is ICD-10-CM Documentation: A How-To Guide for Coders, Physicians and HealthCare Facilities (2014); Chapter 19, pages 341-342.
Medicare local coverage determination (LCD) for chiropractic, specifically Noridian, lists the strain and sprain codes for the spine with only the A extension, as it refers to care that is active therapy (think AT modifier for CMT as required by Medicare). Use of codes with a D extension is not payable by Noridian Medicare and this diagnosis indicates the patient is not under active (corrective) care.
National Government Services, another multistate Medicare intermediary, also lists only the strain and sprain codes with the A extensions, but also codes with the S extension for sequelae. Sequelae refers to the complications or conditions that arise as a direct result of an injury (residual effects). These residual effects can be pain, scar tissue, loss of range of motion, etc.
Generally, a sequelae code such as S13.4XXS is coded secondary to the sequelae itself. For instance, residual pain in the cervical spine following a sprain would be coded in this manner:
- M54.2: cervical pain as primary
- S13.4XXS, indicating the pain is the sequelae of a cervical sprain
While it is the provider's duty to choose the most appropriate code, you must also have a correct understanding of the code meanings. For strain and sprain codes in ICD-10, the A extension does indicate initial encounter, but also covers all dates of service when there is active care. Therefore, the most likely code a chiropractic provider would use, unless the care is no longer active, corrective or acute, would be the A extension.
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