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ICD10BillableValid for clinical use

ICD-10 Code S66.101: Unspecified injury of flexor muscle, fascia and tendon of left index finger at wrist and hand level

S66.101 is a billable ICD-10 diagnosis code used to classify Unspecified injury of flexor muscle, fascia and tendon of left index finger at wrist and hand level in medical records and claims. You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records. ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Injury, poisoning and certain other consequences of external causes (S00-T88).

Reviewed by HealthAssure Clinical TeamUpdated 21 May 2026

What is this code?

ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Injury, poisoning and certain other consequences of external causes (S00-T88).

When is it used?

  • May be used when a clinician documents unspecified injury of flexor muscle, fascia and tendon of left index finger at wrist and hand level in a patient's medical record.
  • May appear in hospital records, claims, referrals, and clinical documentation.
  • This code can be used as a clinically usable diagnosis entry in standardized coding workflows.

What it does not mean

  • A code alone does not explain severity, treatment plan, or outcome.
  • A medical code should not be treated as a substitute for a doctor's diagnosis or advice.

Code hierarchy

chapter
19Injury, poisoning and certain other consequences of external causes (S00-T88)
block
S60-S69Injuries to the wrist, hand and fingers
category
S66Injury of muscle, fascia and tendon at wrist and hand level
category
S66.1Injury of flexor muscle, fascia and tendon of other and unspecified finger at wrist and hand level
category
S66.10Unspecified injury of flexor muscle, fascia and tendon of other and unspecified finger at wrist and hand level
currentS66.10

Where you may see this code

You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.

Related specialists

Emergency Medicine SpecialistOrthopedic Specialist

Related codes

S66.100Unspecified injury of flexor muscle, fascia and tendon of right index finger at wrist and hand levelcodeS66.102Unspecified injury of flexor muscle, fascia and tendon of right middle finger at wrist and hand levelcodeS66.103Unspecified injury of flexor muscle, fascia and tendon of left middle finger at wrist and hand levelcodeS66.104Unspecified injury of flexor muscle, fascia and tendon of right ring finger at wrist and hand levelcodeS66.105Unspecified injury of flexor muscle, fascia and tendon of left ring finger at wrist and hand levelcodeS66.106Unspecified injury of flexor muscle, fascia and tendon of right little finger at wrist and hand levelcodeS66.107Unspecified injury of flexor muscle, fascia and tendon of left little finger at wrist and hand levelcodeS66.108Unspecified injury of flexor muscle, fascia and tendon of other finger at wrist and hand levelcodeS66.109Unspecified injury of flexor muscle, fascia and tendon of unspecified finger at wrist and hand levelcode

Sibling codes

S66.100Unspecified injury of flexor muscle, fascia and tendon of right index finger at wrist and hand levelbillableS66.102Unspecified injury of flexor muscle, fascia and tendon of right middle finger at wrist and hand levelbillableS66.103Unspecified injury of flexor muscle, fascia and tendon of left middle finger at wrist and hand levelbillableS66.104Unspecified injury of flexor muscle, fascia and tendon of right ring finger at wrist and hand levelbillableS66.105Unspecified injury of flexor muscle, fascia and tendon of left ring finger at wrist and hand levelbillableS66.106Unspecified injury of flexor muscle, fascia and tendon of right little finger at wrist and hand levelbillableS66.107Unspecified injury of flexor muscle, fascia and tendon of left little finger at wrist and hand levelbillableS66.108Unspecified injury of flexor muscle, fascia and tendon of other finger at wrist and hand levelbillableS66.109Unspecified injury of flexor muscle, fascia and tendon of unspecified finger at wrist and hand levelbillable

Coding guidelines

Common synonyms

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

Frequently asked questions

Code details

CodeS66.101
SystemICD10
Display nameUnspecified injury of flexor muscle, fascia and tendon of left index finger at wrist and hand level
ChapterInjury, poisoning and certain other consequences of external causes (S00-T88)
BlockInjuries to the wrist, hand and fingers

Flags

BillableYes
Valid clinical useYes

Source

SourceICD-10
Version2026-annual
Releaseannual
Year2026

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.

ICD-10 Code S66.101 for Unspecified injury of flexor muscle, fascia and tendon of left index finger at wrist and hand level | HealthAssure