Unsp inj intrns musc/fasc/tend l thm at wrs/hnd lv, sequela

This code signifies a long-term complication or late effect resulting from an unspecified injury to the intrinsic muscles, fascia, or tendons of the left thumb, specifically at the wrist or hand level. This refers to conditions that arise after the acute phase of the original injury has passed, such as chronic pain, stiffness, or functional impairment.

Use this code when documenting a patient presenting with a current condition directly attributable to a past, unspecified injury of the intrinsic muscles, fascia, or tendons of their left thumb. This applies to follow-up encounters where the sequela of the original injury is being treated or evaluated, rather than the initial acute injury itself.

• Always sequence the sequela code (S66.402S) first, followed by any codes for the specific manifestation of the sequela (e.g., chronic pain, scar formation).
• Ensure the medical record clearly documents the link between the current condition and the past unspecified injury to the left thumb's intrinsic structures.
• This code is for unspecified injury; if the specific type of injury (e.g., strain, tear) is known, a more specific code from the S66.4 category should be used with the appropriate seventh character for sequela.