ICD-10 code S56.125S: Right ring finger flexor tendon laceration

Key takeaways

S56.125S is the ICD-10-CM code for laceration of flexor muscle, fascia and tendon of right ring finger at forearm level, sequela

The code is billable and valid for HIPAA-covered transactions in the FY2026 edition, effective October 1, 2025

Within the S56.12- sub-block the 6th character carries the digit and the side: odd is right, even is left

The 7th character S denotes a sequela encounter: coding a complication that arose from a prior injury, not the original injury visit

Practice management software like Pabau links the diagnosis code to the clinical record at the point of care

ICD-10 code S56.125S covers laceration of flexor muscle, fascia and tendon of the right ring finger at forearm level, sequela. It is billable, and it applies after the original laceration has healed. The patient is back for a residual problem, such as a tendon adhesion or grip weakness.

The 7th character S is what marks the visit as a sequela encounter rather than active treatment. S56.125S sits in the ICD-10-CM system maintained by the National Center for Health Statistics (NCHS) and updated annually by CMS. The FY2026 edition became effective October 1, 2025 and runs through September 30, 2026.

ICD-10 code S56.125S at a glance

Here is the detail coders and billers reach for most often on this code.

Verify the POA exempt status against the current CMS ICD-10 codes page before submitting, as this status can change across fiscal years.

What S56.125S describes

Each element of the description carries a distinct clinical and coding meaning. Breaking it down removes ambiguity at chart audit time.

• Laceration: an open wound caused by a tearing or cutting force, distinct from a strain, sprain, or contusion
• Flexor muscle, fascia and tendon: the code captures all three structures when they are involved. Flexor muscles close the fingers and grip, fascia is the connective sheath, and the tendon connects muscle to bone
• Right ring finger: laterality and finger specificity are both required; the ring finger is the 4th digit of the right hand
• At forearm level: the injury zone is the forearm, not the hand or wrist; forearm-level coding corresponds to tendon zones commonly referenced in surgical planning
• Sequela: the patient is presenting with a late effect rather than the laceration itself. The complication or residual condition arose directly from a previous laceration

This code is mainly used by clinicians treating the aftermath of a prior ring finger flexor laceration at the forearm. Typical presentations are tendon adhesions, range-of-motion deficits, and functional impairment.

Accurate clinical record documentation that ties the current presentation to the original injury supports clean claim submission.

Where S56.125S sits in the code hierarchy

Understanding where S56.125S sits in the ICD-10-CM hierarchy helps coders navigate the tabular list and supports accurate principal-diagnosis sequencing.

Sequela presentations from earlier forearm tendon lacerations turn up most often in occupational therapy and sports medicine settings. Category S56 covers every forearm-level muscle, fascia, and tendon injury, so coders in these specialties meet sibling codes from this block regularly.

Understanding the 7th character: S for sequela

The 7th character extension turns S56.125 from an unbillable placeholder into a specific, reimbursable diagnosis code. The ICD-10-CM Official Guidelines, Section I.C.19, define three encounter types for injury codes.

The critical distinction: sequela (S) is not the same as subsequent encounter (D). Subsequent encounter means the original wound is still healing. Sequela means the original injury has resolved but left a residual condition. Confusing these two is a documented source of payer edits.

Not every injury category stops at three options. Fracture codes add 7th characters for healing status, such as P for malunion in S62.163P. Laceration codes like S56.125S use only A, D, and S.

When coding sequela, the residual condition is sequenced first, and the code for the nature of the sequela (S56.125S) follows.

Take a patient presenting with tendon adhesion of the right ring finger after a prior forearm laceration. The adhesion is the primary diagnosis, and S56.125S follows as the secondary code that explains causation.

Billable status and reimbursement

S56.125S is a billable, specific ICD-10-CM code. It can be submitted on claims for HIPAA-covered transactions. Coders should confirm currency through the CDC/NCHS ICD-10-CM web tool, which reflects the current FY release.

• Billable status: Yes, valid for claim submission
• HIPAA compliance: Valid for HIPAA-covered transactions
• POA reporting: sequela codes are generally exempt from Present on Admission reporting, because the condition did not arise during the current hospital stay. Verify against the official CMS POA exempt code list for FY2026
• Effective date: October 1, 2025, through September 30, 2026 (FY2026 edition)

Practices using claims management software can embed diagnosis code validation into the billing workflow, flagging unbillable parent codes like S56.125 before submission.

Integrating ICD-10 code lookup with the patient record reduces the manual scrubbing step. It also heads off the common S56.125 versus S56.125S confusion at point of entry.

S56.125S vs related codes: Sibling and parent comparison

Coders working across forearm tendon injuries meet several near-neighbor codes. The table below covers the siblings that are easiest to confuse with S56.125S. The three encounter-type variants are covered in the 7th character table above.

How the 6th character encodes finger and side

Every code in the S56.12- sub-block carries both the digit and the side in its 6th character. The pattern is strict. Odd digits are the right hand, even digits are the left, working outward from the index finger.

• S56.121 / S56.122: right / left index finger (2nd digit)
• S56.123 / S56.124: right / left middle finger (3rd digit)
• S56.125 / S56.126: right / left ring finger (4th digit)
• S56.127 / S56.128: right / left little finger (5th digit)
• S56.129: unspecified finger, to be avoided when the record names the digit

S56.125 is therefore the right ring finger, and S56.126 the left. The thumb is not in this sub-block at all, because thumb flexor injuries at forearm level sit under S56.0-.

Reading the 6th character one position out is the most common cause of laterality denials here. The same odd-right, even-left rule runs through the S56.11- strain sub-block, where the left middle finger sequela is S56.114S. Misreading the digit can land a claim in strain codes instead of laceration codes.

Approximate synonyms and index references

The ICD-10-CM Alphabetic Index may route coders to this code from several different clinical terms. Recognizing the alternate descriptions helps when you cross-reference operative notes or discharge summaries with non-standard phrasing.

• Sequela of laceration of flexor tendon of right ring finger at forearm
• Late effect of right ring finger flexor muscle laceration, forearm level
• Right 4th digit flexor tendon laceration sequela, forearm
• Residual deficit following flexor tendon cut, right ring finger, forearm zone
• Tendon injury sequela, ring finger right hand, forearm level

When reviewing operative notes, coders may also encounter references to tendon zones. For forearm-level lacerations, this corresponds to the proximal zones used in surgical hand therapy classification.

The AAPC Codify ICD-10-CM lookup tool supports index-to-code tracing for alternate clinical terminology.

Clinical context: Flexor tendon laceration at forearm level

Flexor tendon lacerations at the forearm level typically occur from sharp-force trauma: glass injuries, knife lacerations, or industrial accidents. The forearm houses the flexor digitorum superficialis and flexor digitorum profundus tendons, which travel distally to control finger flexion.

Sequela presentations in this anatomy most commonly include tendon adhesions restricting range of motion, grip strength deficits, and tendon rupture following incomplete repair. These are the conditions that prompt a return to care after the original injury has healed, and they are what S56.125S captures.

• Tendon adhesion: scar tissue binding the repaired tendon to its sheath, reducing glide and finger flexion
• Grip weakness: residual motor deficit from incomplete tendon healing or nerve involvement at the time of the original laceration
• Re-rupture: failure of the tendon repair, presenting as sudden loss of active flexion in a previously treated patient

The patient record should note the date and nature of the original laceration. It should also carry the current residual symptom and the causal link between the two. That supports the sequela coding logic and reduces the risk of payer queries.

Objective measures make the link harder to dispute. A recorded two-point discrimination test result or a grip strength reading gives a reviewer something to check. Digital intake forms help too, because they capture prior injury history alongside the current findings.

Billing steps for a sequela encounter

Sequela coding follows a specific sequencing rule that differs from initial and subsequent encounter coding. Following these steps reduces payer edits on S56.125S claims.

1. Confirm the injury has resolved. Sequela applies only after the original laceration has healed. If the patient is still in the active healing phase, use S56.125D (subsequent encounter), not S56.125S.
2. Code the residual condition first. Per ICD-10-CM guidelines, sequence the nature of the sequela (e.g. tendon adhesion) as the principal diagnosis. S56.125S follows as the causal injury code.
3. Do not use S56.125S for the original injury encounter. Submitting S56.125S on the initial visit or during active treatment will result in a payer mismatch. The correct code for active treatment is S56.125A.
4. Confirm POA status. For inpatient claims, sequela codes are generally POA exempt. Confirm against the CMS POA exempt list for FY2026 before submission.
5. Document the causal link. The clinical note should explicitly state the prior laceration as the cause of the current condition. Vague notes referencing only the current symptom without linking to the original injury create audit risk.

Practices with a steady volume of post-injury follow-ups can cut miscoding risk by making the encounter type a required field. Surfacing the A, D, or S choice in the software you already use for HIPAA compliance stops it being picked from memory.

Sequela visits often carry a procedure alongside the diagnosis. Tenolysis and tendon sheath work at the forearm sits in its own code range, including 25110. The diagnosis on the claim has to support whatever was done.

Excludes notes and coding considerations

Category S56 carries coding notes that affect which codes can and cannot be used together. Coders should review these before submitting claims involving forearm tendon injuries.

• Excludes injuries at wrist and hand level (S66): S56 codes apply only to injuries at the forearm. If the tendon was cut at the wrist or hand, the S66 category applies. A dislocation at that level takes a code such as S63.004S.
• Excludes muscle strain (S56.11-): strain and laceration are different injury types. Do not use a laceration code when the documentation supports strain only.
• Sprain is not coded here: sprains of the forearm region use a different category. S56.125S is specific to lacerations involving the flexor structures.
• Open wound without tendon involvement: when the note describes a residual forearm wound and no flexor damage, S51.801S is the closer code.

When the injury level is in doubt, the operative note or imaging report settles it. Either one will say whether the laceration sits at the forearm or at the wrist and hand. Coding from an ambiguous description without that confirmation is a compliance risk.

Automated clinical workflows can prompt for the anatomical detail while the clinician is still in the note. That is cheaper than chasing the answer after a claim rejects.

How practice management software supports accurate sequela coding

Coders often look up S56.125S in one system, confirm it is billable, then re-key it into another to build the claim. The code survives that hop. The causal link back to the original laceration usually does not, and payers query sequela claims on exactly that.

Practice management software like Pabau removes the second step. The clinician documents the visit, the diagnosis code attaches to that same record, and the claim is built from it without re-entry.

For physical therapy and hand therapy caseloads, sequencing is the harder part. A standalone code lookup cannot enforce it. A record that drives the claim can prompt for the residual condition first, then the injury code.

Pabau builds claims from structured clinical records, so you can template a follow-up note for sequela visits. Give it fields for the original injury date, the current residual symptom, and the causal link between them.

Coders then get the laterality, the digit, and the encounter type from the note rather than from memory. So you spend less time chasing providers for clarification and see fewer rejections on sequela claims.

Track ICD-10 codes inside your clinical workflow

Pabau's claims management software lets you attach diagnosis codes to the patient record at the point of care. That cuts coding errors and claim rejections on musculoskeletal injury visits.

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Conclusion

Treat the 7th character as a documentation question rather than a coding one. If the note says the laceration has healed and names the residual problem, S56.125S will hold up. If it does not, careful code selection will not save the claim.

The habit worth building is a small one. Ask for the original injury date and the current residual finding before the claim leaves the practice. Coders who have both rarely have to guess between A, D, and S.

That is easier when the diagnosis code and the note live on the same record. Book a demo to see how Pabau attaches ICD-10 codes at the point of care and builds the claim from them.

Continue your research

Working the same forearm from the fracture side? S52.591S covers sequela reporting after a lower radius fracture.

Billing surgery on the digit itself? 20822 sets out the replantation rules, including the modifiers payers check.

Need the arthrotomy code for a finger joint? 26080 explains the documentation that supports it.

Ruling out a wrist injury before you code the forearm? Scaphoid fracture test shows how the exam narrows down the injury level.

Frequently asked questions

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