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S66.421S vs S66.429S

S66.421S (Laceration of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level, sequela) compared with S66.429S (Laceration of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, sequela), from the official CMS tabular data. S66.421S and S66.429S code the same condition on opposite sides. MedCoder-derived

Relationship

Review

Laterality relationship

S66.421S
Right
Laceration of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level, sequela
S66.429S
Unspecified
Laceration of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, sequela

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. S66.421S and S66.429S 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

S66.421SLaceration of intrinsic muscle, fascia and tendon of right thumb at wrist and hand level, sequelaS66.429SLaceration of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, sequela
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 right thumb at wrist and hand level, sequela is a billable ICD-10-CM diagnosis code (S66.421S).Laceration of intrinsic muscle, fascia and tendon of unspecified thumb at wrist and hand level, sequela is a billable ICD-10-CM diagnosis code (S66.429S).
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