ICD code T22.629S – Second-degree corrosion of unspecified elbow, sequela

Key takeaways

ICD-10 code T22.629S is billable and valid for FY 2026. It covers corrosion of second degree of unspecified elbow, sequela.

The site is the elbow, not a generic upper limb. In T22.6-, the 5th character carries the site and the 6th carries laterality.

The 9 does not mean left. Left elbow is T22.622S and right elbow is T22.621S, so use those whenever the chart names a side.

Sequencing runs the other way round from what most coders expect. The residual scar or contracture is listed first, and T22.629S follows it.

Practice management software like Pabau submits claims straight from the patient record, and checks insurer membership and authorization details first.

ICD-10 code T22.629S covers a healed chemical burn of the elbow

ICD-10 code T22.629S is a billable, specific ICD-10-CM diagnosis code, valid for FY 2026 claims. Its official descriptor reads Corrosion of second degree of unspecified elbow, sequela.

Four elements define it. The mechanism is corrosion, which ICD-10-CM uses for a chemical burn rather than a thermal one. The depth is second degree, meaning blisters and partial-thickness loss.

The site is the elbow. The encounter type is sequela, so the patient is being treated for a late effect of the corrosion rather than for the corrosion itself.

Laterality is the one element the code does not carry. That final 9 before the S tells the payer the record never named which elbow. It does not stand for the left side, and reading it that way causes the most common error on this code.

Each character in T22.629S carries one fact

Read the code one character at a time and the ambiguity disappears. The T22.6- subcategory splits site and laterality across two positions. A coder who treats the 6th character as part of the site description lands on the wrong limb.

That 5th character runs through the whole T22.6- subcategory in a fixed order:

• 0 for an unspecified site
• 1 for the forearm
• 2 for the elbow
• 3 for the upper arm
• 4 for the axilla
• 5 for the shoulder
• 6 for the scapular region
• 9 for multiple sites

When the 5th character is 0, the site is unknown. There is no side to report, so ICD-10-CM inserts a placeholder X in the 6th position, giving T22.60XS.

Where T22.629S sits in the ICD-10-CM hierarchy

Each level narrows the clinical picture until the fully specified child code is reached. Walking the ladder takes seconds, and it catches a parent code that slipped onto the claim in place of the billable one.

T22.629 is a six-character subcategory and is not billable on its own. Every code in category T22 requires a 7th character, so a claim carrying T22.629 without A, D, or S is rejected as invalid.

The 7th character S belongs to late-effect visits only

S marks a sequela encounter. The patient is being treated for a condition the earlier corrosion left behind, rather than for the corrosion itself.

The FY 2026 ICD-10-CM Official Guidelines for Coding and Reporting are explicit in Section I.C.19.a. The S is added only to the injury code, never to the sequela code. The type of sequela is sequenced first, and the injury code follows it.

Section I.C.19.d.7 then confirms that late effects of burns and corrosions are what the S character is built for, scars and joint contractures included. Leaving the A character on a scar revision months after the original burn is a frequent slip.

The line between D and S causes most of the confusion, so here is what each character actually covers.

Sequencing puts T22.629S second, never first

Sequencing is where this code goes wrong most often. Section I.B.10 says that coding a sequela usually takes two codes. The condition or nature of the sequela is sequenced first, and the sequela code second.

T22.629S is the sequela code, so the residual condition leads the claim. That is M24.529 for a contracture of the unspecified elbow, or L90.5 for scar conditions and fibrosis of skin. Which one leads depends on what is being treated today.

Add the Code first note at T22.6 and the finished claim looks like this.

T22.629A, T22.629D, and T22.629S differ by one character

The three sibling codes share one descriptor and differ only in the 7th character. Which one applies depends on where the patient is in their recovery.

One nuance gets missed. The D code covers routine follow-up during healing, and it is not a sequela code. Once the corrosion has healed and the visit is only about what it left behind, the character switches to S.

Section I.C.19.d.8 also allows two of them on one record. Say a patient has a fresh corrosion on one arm and an old scar on the other. That record carries an A or D code alongside an S code.

Three levels of instructional notes apply to T22.629S

ICD-10-CM attaches notes at the block, the category, and the subcategory, and all of them reach this code. Includes notes define the terms, Excludes2 notes name what may be reported alongside it, and Code first notes fix the order.

• Includes (T20-T25 block): the block-level note defines the degrees for every code beneath it. Second degree is given as blisters and epidermal loss, and the chart has to support that finding.
• Excludes2 (T22 category): burn and corrosion of interscapular region (T21.-) and burn and corrosion of wrist and hand (T23.-). Excludes2 means these sit outside T22 but can be reported alongside it. A patient with corrosion of both the elbow and the hand gets a code from each category.
• Code first (T22.6 subcategory): a code from T51-T65 to identify the chemical and the intent. The chemical code is sequenced ahead of the corrosion code.
• Use additional code (T22.6 subcategory): an external cause code to identify the place of occurrence (Y92).
• Use additional code (T20-T25 block): a code from T31 or T32 for the extent of body surface involved. Section I.C.19.d.6 bars T31 and T32 on sequelae of burns and corrosions, so that note does not apply to a T22.629S claim.
• Burn versus corrosion: T22.6- codes are for chemical injury only. A thermal second-degree burn of the same site is T22.229S at sequela. The two families are not interchangeable.

A corrosion code never travels without its chemical code

The Code first note at T22.6 requires a code from T51-T65 that identifies the chemical and the intent. Leaving it off is one of the most common reasons corrosion claims get flagged by payers.

For corrosive substances, that range narrows to category T54, toxic effect of corrosive substances. These are combination codes. The 6th character carries the intent, with 1 for accidental, 2 for intentional self-harm, 3 for assault, and 4 for undetermined.

Because intent is built in, Section I.C.19.e confirms that no separate external cause code is needed for the substance itself. A place of occurrence code from Y92 is still added under the Use additional code note at T22.6.

Key rule: both codes describe the same encounter, so the T54 code carries the same 7th character as the corrosion code. On a sequela claim that means S on both, giving a pairing such as T54.2X1S with T22.629S.

Related elbow codes to check before you settle on T22.629S

T22.629S sits in a family of codes that share the elbow site but differ in laterality, in depth, or in mechanism. The first two rows are the ones to reach for whenever the record names a side.

That last row is worth holding on to. T22.60XS covers a record that never says which part of the limb was burned. T22.629S covers a record that names the elbow but not the side.

Where the sub-site is something other than the elbow, the code moves to the matching 5th character, such as T22.619S for the forearm. Our ICD-10-CM code index lists the rest of the T22 family, and the CDC and NCHS ICD-10-CM web tool handles a quick one-off lookup.

What second-degree corrosion looks like in the chart

Corrosion is the ICD-10-CM term for a chemical burn. Thermal, electrical, and radiation injuries belong to the burn codes instead. The official guidelines put it plainly. Corrosions are burns due to chemicals, and the coding rules for both are the same.

Second degree means partial-thickness injury involving the epidermis and the superficial dermis. The Includes note at the head of the T20-T25 block defines the three depths in terms a coder can match to a chart:

• First degree: erythema.
• Second degree: blisters and epidermal loss.
• Third degree: full-thickness skin loss with deep necrosis of underlying tissue.

Depth comes from the clinical findings documented at the encounter. The chemical involved and its concentration do not decide it.

The elbow is one of seven named sites inside T22. That category spans the shoulder and upper limb, but stops short of the wrist and hand. A corrosion that crosses from the elbow into the forearm is coded to the site the provider documents. Injuries confined to the wrist or hand belong in T23.

Five checks before a T22.629S claim leaves your desk

The note, the code sequence, and the companion codes all have to agree before the claim goes out. These five checks, run in order, catch the errors behind most denials on this code.

1. Look for the side before you accept unspecified. Scan the whole record, nursing and wound-care notes included, for a right or left elbow. If a side is named anywhere, use T22.621S or T22.622S. If the record conflicts, query the provider.
2. Confirm the encounter type. Use S when the corrosion has healed and the visit is for a residual condition. Use D for routine care during healing, and A while active treatment is still being given.
3. Sequence the residual condition first. Per Section I.B.10, the condition leads and T22.629S follows. The claim opens with a contracture code such as M24.529, or a scar code such as L90.5.
4. Add the chemical and intent code. Pick the T51-T65 code matching the documented substance, usually from T54. Put the intent in the 6th character and the same S in the 7th, then add a Y92 place of occurrence code.
5. Document the causal link. The note has to state that the current condition is a direct consequence of the earlier corrosion. A note describing only the presenting symptom will not survive an audit.

From there the claim travels the usual route. It leaves the practice for the clearinghouse, reaches the payer, and comes back as a remittance.

Seventh-character mismatches tend to surface at that last step. The denial reason points at an invalid code combination when the chemical and injury codes disagree. A steady denial management routine catches the pattern early, before it turns into a stack of unpaid balances.

How Pabau keeps the note and the T22.629S claim together

Most practices code a corrosion sequela in two places at once. The clinical note sits in the patient record, the code list sits in a browser tab, and the claim is built in a third system.

Each switch between them is a chance to lose a documented side. It is also how the S slips off one code and not the other.

Pabau, practice management software for medical and aesthetic practices, keeps the record and the claim in one system. Its claims software for practices builds the claim straight from the patient record. Insurer membership and authorization details are checked before that claim is submitted.

The result is fewer corrections after the fact. A laterality or sequencing error shows up while the chart is still open. The provider is still there to answer a query, so the fix happens before the claim goes out.

Build the claim where the note already lives

Pabau builds claims straight from the patient record, and checks insurer membership and authorization details before submission. See how it works for practices treating burn and wound patients.

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Conclusion

T22.629S describes a second-degree chemical burn of the elbow, seen at a late-effect visit, on a record that never named the side.

Two mistakes account for most of the trouble it causes. The 9 gets read as left when it only ever means unspecified. The code gets sequenced first when the guidelines put the scar or the contracture ahead of it.

Both start as documentation problems, so the fix sits upstream of the claim. Query the side while the chart is still open, and the unspecified code stops appearing on claims that never needed it. Book a demo to see how Pabau builds burn and wound claims from the patient record.

Continue your research

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