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S56.399Non-billableSave

S56.399 - Other injury of extensor or abductor muscles, fascia and tendons of unspecified thumb at forearm level

ICD-10-CM Chapter 19: Injury, poisoning and certain other consequences of external causes · S50-S59 Injuries to the elbow and forearm (S50-S59) · Subcategory of S56.39 · FY2027

Coding Guidance

S56.399 requires a 7th character. Report the code below that matches the documentation, for example A for initial encounter, D for subsequent encounter, S for sequela.

7th Character

The appropriate 7th character is to be added to each code from category S56

Includes, Excludes and Coding Notes

Excludes 2 — Not Included HereFrom S56

Not part of this code; report both codes when the patient has both conditions.

  • injury of muscle, fascia and tendon at or below wrist (S66.-)
  • sprain of joints and ligaments of elbow (S53.4-)
Code AlsoFrom S56

Report an additional code when both conditions apply.

  • any associated open wound (S51.-)
Excludes 2 — Not Included HereFrom S50-S59 Injuries to the elbow and forearm (S50-S59)

Not part of this code; report both codes when the patient has both conditions.

  • burns and corrosions (T20-T32)
  • frostbite (T33-T34)
  • injuries of wrist and hand (S60-S69)
  • insect bite or sting, venomous (T63.4)
Excludes 2 — Not Included HereFrom Chapter S00-T88

Not part of this code; report both codes when the patient has both conditions.

  • birth trauma (P10-P15)
  • obstetric trauma (O70-O71)
Use Additional CodeFrom Chapter S00-T88

Add a secondary code to identify the associated condition or cause when it is documented.

  • code to identify any retained foreign body, if applicable (Z18.-)
NotesFrom Chapter S00-T88

Instructional notes from the ICD-10-CM tabular list.

  • Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
  • The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.

More Specific Codes (3)

S56.399AOther injury of extensor or abductor muscles, fascia and tendons of unspecified thumb at forearm level, initial encounter→S56.399DOther injury of extensor or abductor muscles, fascia and tendons of unspecified thumb at forearm level, subsequent encounter→S56.399SOther injury of extensor or abductor muscles, fascia and tendons of unspecified thumb at forearm level, sequela→

Related condition guides

Documentation requirements, coding pitfalls and FAQs for conditions coded with S56.399.