The seventh character in the ICD-10 code structure is perhaps the most misunderstood part of a diagnosis code. 
The seventh character extension alpha suffix you select will be dependent on what ICD-10 chapter it is being used in.
- Chapter 13: Diseases of the Musculoskeletal System – Encounter (Coding pathological fractures)
- Chapter 15: Pregnancy, Childbirth and the Puerperium – Fetus identification
- Chapter 18: Symptoms, Signs, and Abnormal Clinical and Laboratory Findings, Not Elsewhere
Classified – Comma scale
- Chapter 19: Injury, Poisoning, and Certain Other Consequences of External Causes – Encounter
- Chapter 20: External Causes of Morbidity – Encounter
- Chapter 21: Factors influencing Health Status and Contact with Health Services – Encounter
Note: A patient may be seen by different or new providers over the course of treatment for an injury. The assignment of the seventh character digit would be dependent on whether the patient is undergoing active treatment (D or S) and not dependent on whether the provider is seeing the patient for the first time. Seventh Character Alpha Prefix Extensions are used to indicate the episode of care of the patient. The general three options are available as seventh character extensions:
- A, initial encounter (initial episode of care for the injury, initial provider of care first visit)
- D, subsequent encounter (follow-up visits regardless of provider new/established patient)
- S, sequela (complications or conditions resulting from injury, regardless of provider new/established)
Note: Remember seventh character extensions also are required for some pregnancy complication codes. In that case, the seventh character indicates which fetus is affected.
Fracture Care Treatment
The 7th character alpha prefixes are a bit more extensive and more complicated still, adding the type of fracture into the mix with episode of care, with seven options available:
- A, initial encounter for closed fracture
- B, initial encounter for open fracture
- D, subsequent encounter for fracture with routine healing
- G, subsequent encounter for fracture with delayed healing
- K, subsequent encounter for fracture with nonunion
- P, subsequent encounter for fracture with malunion
- S, sequela (complications or conditions resulting from injury)
Example: An article at “Implement HIT” offers an example: “a patient may be seen in the Emergency Department for a fractured ankle, then referred to their family physician for follow- up, and then subsequently referred to an orthopedic surgeon for treatment and ultimately, surgery. All three providers would code the ankle fracture using the seventh character ‘A’ because the patient is still receiving active treatment for the fracture.” On the other hand, an example from the “ICD-10 Trainer blog” shows a patient who fractured his ankle while on vacation and was treated in the Emergency Department (and coded with a seventh character extension of “A” for that initial encounter). When that same patient followed up with another doctor back in his hometown three weeks later and that doctor confirmed that everything was healing up just right, the coder would choose seventh character extension “D.”
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