Alphabetic Index FY2027

S66.124S

Laceration of flexor muscle, fascia and tendon of right ring finger at wrist and hand level, sequela

FY2027Chapter 19: Injury, poisoning and certain other consequences of external causes/S60–S69 Injuries to the wrist, hand and fingers

BillableComplete code, valid to report
Care settingsHome Health Primary · Wound

S66.124S (also written S66124S) is a billable ICD-10-CM diagnosis code for laceration of flexor muscle, fascia and tendon of right ring finger at wrist and hand level, sequela. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 540 codes in category S66 (Injury of muscle, fascia and tendon at wrist and hand level). Its 7th character, S, means sequela. Its coding notes include a Use additional code instruction, a Code also instruction and 7 Excludes2 entries.

7th character

Category S66 requires a 7th character.

Assembled code S66.124S Open code

Guidelines tips

From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.

The 7th character depends on whether the patient is in active treatment, not on who sees the patient. An aftercare Z code is not used for injury aftercare.

Guidelines I.C.19.aInjuries: application of 7th charactersRead the official text

Each injury gets its own code unless a combination code exists, with the most serious injury first. Superficial injuries at the same site as a more severe injury are not coded. Injuries during medical care are coded as complications.

Guidelines I.C.19.bCoding of injuriesRead the official text

Use additional code

Add the listed code as a secondary code, if known.

Also from chapter/block level (1 note)
Inherited from Chapter 19 Injury, poisoning and certain other consequences of external causes
  • code to identify any retained foreign body, if applicable (Z18.-)

Code also

Two codes may be needed to describe the condition. This note gives no sequencing order.

Inherited from S66 Injury of muscle, fascia and tendon at wrist and hand level
  • any associated open wound (S61.-)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Inherited from S66.1 Injury of flexor muscle, fascia and tendon of other and unspecified finger at wrist and hand level
  • Injury of long flexor muscle, fascia and tendon of thumb at wrist and hand level (S66.0-)
Inherited from S66 Injury of muscle, fascia and tendon at wrist and hand level
  • sprain of joints and ligaments of wrist and hand (S63.-)
Also from chapter/block level (5 notes)
Inherited from S60–S69 Injuries to the wrist, hand and fingers
Inherited from Chapter 19 Injury, poisoning and certain other consequences of external causes
  • birth trauma (P10-P15)
  • obstetric trauma (O70-O71)

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

Home Health Primary

Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the Wound clinical group.

Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026

Notes

Also from chapter/block level (2 notes)
Inherited from Chapter 19 Injury, poisoning and certain other consequences of external causes
  • Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
  • The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.