S66.128A vs S66.128S

S66.128A (Laceration of flexor muscle, fascia and tendon of other finger at wrist and hand level, initial encounter) compared with S66.128S (Laceration of flexor muscle, fascia and tendon of other finger at wrist and hand level, sequela), from the official CMS tabular data. S66.128A and S66.128S code the same injury at a different phase of treatment. MedCoder-derived

Relationship

Review

Encounter relationship

S66.128A

Initial encounter

Laceration of flexor muscle, fascia and tendon of other finger at wrist and hand level, initial encounter

↔

S66.128S

Sequela

Laceration of flexor muscle, fascia and tendon of other finger at wrist and hand level, sequela

Same underlying diagnosis, different encounter phase.

The 7th character records the phase of care for the encounter being coded, so a single encounter takes one of these characters, not several. Review whether both phases belong on the same episode of care.

Source: ICD-10-CM Official Guidelines, Section I.C.19.a

Can these codes be reported together?

Same injury, other encounter phase. S66.128A and S66.128S code the same injury at a different phase of treatment, set by the 7th character.

The 7th character records the type of care given at the encounter being coded (ICD-10-CM Official Guidelines, Section I.C.19.a), so one encounter takes one of these, not both.

Side by side

	S66.128ALaceration of flexor muscle, fascia and tendon of other finger at wrist and hand level, initial encounter	S66.128SLaceration of flexor muscle, fascia and tendon of other finger at wrist and hand level, sequela
Billing status	Billable	Billable
Classification	S00-T88 — Injury, poisoning and certain other consequences of external causes	S00-T88 — Injury, poisoning and certain other consequences of external causes
Definition	Laceration of flexor muscle, fascia and tendon of other finger at wrist and hand level, initial encounter is a billable ICD-10-CM diagnosis code (S66.128A).	Laceration of flexor muscle, fascia and tendon of other finger at wrist and hand level, sequela is a billable ICD-10-CM diagnosis code (S66.128S).
7th character	The appropriate 7th character is to be added to each code from category S66	The appropriate 7th character is to be added to each code from category S66
Includes	Laceration of flexor muscle, fascia and tendon of specified finger with unspecified laterality at wrist and hand level	Laceration of flexor muscle, fascia and tendon of specified finger with unspecified laterality at wrist and hand level

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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources