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S66.320 vs S66.321

S66.320 (Laceration of extensor muscle, fascia and tendon of right index finger at wrist and hand level) compared with S66.321 (Laceration of extensor muscle, fascia and tendon of left index finger at wrist and hand level), from the official CMS tabular data. S66.320 and S66.321 code the same condition on opposite sides.

Relationship

Review

Laterality relationship

S66.320
Right
Laceration of extensor muscle, fascia and tendon of right index finger at wrist and hand level
↔
S66.321
Left
Laceration of extensor muscle, fascia and tendon of left index finger at wrist and hand level

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. S66.320 and S66.321 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

S66.320Laceration of extensor muscle, fascia and tendon of right index finger at wrist and hand levelS66.321Laceration of extensor muscle, fascia and tendon of left index finger at wrist and hand level
Billing statusNon-billable header

Report instead: S66.320A, S66.320D, S66.320S

Non-billable header

Report instead: S66.321A, S66.321D, S66.321S

ClassificationS00-T88 — Injury, poisoning and certain other consequences of external causesS00-T88 — Injury, poisoning and certain other consequences of external causes
DefinitionLaceration of extensor muscle, fascia and tendon of right index finger at wrist and hand level is a non-billable ICD-10-CM category code (S66.320).Laceration of extensor muscle, fascia and tendon of left index finger at wrist and hand level is a non-billable ICD-10-CM category code (S66.321).
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
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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