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S66.422A vs S66.429A

S66.422A (Laceration of intrinsic muscle, fascia and tendon of left thumb at wrist and hand level, initial encounter) compared with S66.429A (Laceration of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, initial encounter), from the official CMS tabular data. S66.422A and S66.429A code the same condition on opposite sides.

Relationship

Review

Laterality relationship

S66.422A
Left
Laceration of intrinsic muscle, fascia and tendon of left thumb at wrist and hand level, initial encounter
S66.429A
Unspecified
Laceration of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, initial encounter

Same condition; these differ only in which side is documented.

These codes share a category and title and differ only in the side affected. The documentation decides which applies, and a bilateral code is reported only where the code set provides one.

Source: ICD-10-CM tabular list (laterality variant derived from the code title)

Can these codes be reported together?

Same condition, opposite side. S66.422A and S66.429A name the same condition on opposite sides of the body.

Same category and title, differing only in which side is affected — the documentation decides which one applies, and a bilateral code is reported only where the code set provides one.

Side by side

S66.422ALaceration of intrinsic muscle, fascia and tendon of left thumb at wrist and hand level, initial encounterS66.429ALaceration of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, initial encounter
Billing statusBillableBillable
ClassificationS00-T88 — Injury, poisoning and certain other consequences of external causesS00-T88 — Injury, poisoning and certain other consequences of external causes
DefinitionLaceration of intrinsic muscle, fascia and tendon of left thumb at wrist and hand level, initial encounter is a billable ICD-10-CM diagnosis code (S66.422A).Laceration of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, initial encounter is a billable ICD-10-CM diagnosis code (S66.429A).
7th characterThe appropriate 7th character is to be added to each code from category S66The appropriate 7th character is to be added to each code from category S66

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