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S66.121

⚠ Non-billable (Header)

Laceration of flexor muscle, fascia and tendon of left index finger at wrist and hand level

Injury, poisoning and certain other consequences of external causes (S00-T88)

⚠️ This is a category header code — not billable. Use a more specific child code below.

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⚠️ Excludes2

inherited

Rules inherited from parent codes.

S66.1
  • • Injury of long flexor muscle, fascia and tendon of thumb at wrist and hand level (S66.0-)
S66
  • • sprain of joints and ligaments of wrist and hand (S63.-)

Child Codes (3)

S66.121ALaceration of flexor muscle, fascia and tendon of left index finger at wrist and hand level, initial encounterS66.121DLaceration of flexor muscle, fascia and tendon of left index finger at wrist and hand level, subsequent encounterS66.121SLaceration of flexor muscle, fascia and tendon of left index finger at wrist and hand level, sequela

Clinical Description

ICD-10-CM code S66.121 represents laceration of flexor muscle, fascia and tendon of left index finger at wrist and hand level. This code falls under the Injury, poisoning and certain other consequences of external causes (S00-T88) classification. It is a non-billable category header code. A more specific child code from the list below must be used for billing and reimbursement purposes.

This is a 7-character code at the 6th level of specificity. There are 3 more specific child codes under S66.121.

Frequently Asked Questions

What is ICD-10 code S66.121?

ICD-10-CM code S66.121 is "Laceration of flexor muscle, fascia and tendon of left index finger at wrist and hand level". It belongs to the category: Injury, poisoning and certain other consequences of external causes (S00-T88).

Is S66.121 a billable ICD-10 code?

No, S66.121 is a non-billable header code. A more specific child code must be used for billing.

Can S66.121 be coded with other codes?

S66.121 has 2 Excludes2 note(s). These conditions can be coded together if both are documented in the patient record.

Related Codes in S66.12

Other codes in the same category that may be relevant for differential coding:

S66.120Laceration of flexor muscle, fascia and tendon of right index finger at wrist and hand levelS66.122Laceration of flexor muscle, fascia and tendon of right middle finger at wrist and hand levelS66.123Laceration of flexor muscle, fascia and tendon of left middle finger at wrist and hand levelS66.124Laceration of flexor muscle, fascia and tendon of right ring finger at wrist and hand levelS66.125Laceration of flexor muscle, fascia and tendon of left ring finger at wrist and hand levelS66.126Laceration of flexor muscle, fascia and tendon of right little finger at wrist and hand levelS66.127Laceration of flexor muscle, fascia and tendon of left little finger at wrist and hand levelS66.128Laceration of flexor muscle, fascia and tendon of other finger at wrist and hand levelS66.129Laceration of flexor muscle, fascia and tendon of unspecified finger at wrist and hand level

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Code Information

CodeS66.121
BillableNo — Header code
ParentS66.12
CategoryInjury, poisoning and certain other consequences of external causes (S00-T88)
Excludes10 rule(s)
Excludes22 note(s)
Child codes3

Data Source

CMS ICD-10-CM 2026 Tabular List

Updated October 1, 2025 (FY2026)