ICD-10 code S46.191A: Biceps long head injury, right arm

Key takeaways

ICD-10 code S46.191A means other injury of muscle, fascia and tendon of the long head of biceps, right arm, initial encounter.

S46.191A is a billable ICD-10-CM code, valid for HIPAA-covered claims and unchanged in the FY2026 edition effective October 1, 2025.

The code already names the right arm, so the open question is the injury type rather than the anatomy.

The 7th character A covers active treatment. Use S46.191D for later healing visits and S46.191S for a sequela.

Practice management software like Pabau keeps an ICD-10-CM code library inside the patient record, so the code you document seeds the claim form.

ICD-10 code S46.191A covers an “other” injury of the long head of the biceps, right arm, at an initial encounter.

The word “other” makes the code sound like a dumping ground. It’s much narrower than that, because the structure and the side are already fixed. Only the injury type stays open.

That misreading is what sends claims back. A coder sees “shoulder muscle injury” in a note and reaches for a biceps code. Or the chart names the side, yet the claim goes out unspecified anyway. Both mistakes stop once you can read the six characters in front of the A.

What S46.191A covers, in one line

S46.191A means other injury of muscle, fascia and tendon of the long head of biceps, right arm, initial encounter.

It is a billable, specific ICD-10-CM code, so it can stand on its own as a diagnosis. The FY2026 edition took effect on October 1, 2025, and the wording did not change.

Check the wording against the official tabular list before you appeal a denial. The CDC ICD-10-CM browser tool publishes the current entry for every code in the S46 category, including the notes that sit above it.

Why a biceps code sits in the shoulder block

The long head of the biceps starts inside the shoulder. Its tendon anchors at the supraglenoid tubercle of the scapula, crosses the joint, then runs down through the bicipital groove of the humerus. An injury there is anatomically a shoulder problem, which is why S46.1 lives in the S40-S49 block.

The elbow end belongs elsewhere. S46 carries a Type 2 Excludes note for injury of muscle, fascia and tendon at the elbow.

That note sends distal biceps injuries to the S56 category. Type 2 means the two conditions can coexist, so both codes may appear on one claim when the record supports each.

Four nearby boundaries are worth memorizing:

• S46.2 covers other parts of the biceps, so the short head and the rest of the muscle belly sit here.
• S46.3 covers the triceps at the same shoulder and upper arm level.
• M75.21 is bicipital tendinitis of the right shoulder. Overuse and inflammation belong in Chapter 13, not in an injury code.
• S43.43- covers a superior glenoid labrum lesion. A biceps anchor tear that takes the labrum with it is a labral injury, which the biceps load test helps pin down.

The vague part of S46.191A is the injury type

Under S46.1, the 5th character carries the injury type and the 6th carries the side. Coders often read it the other way around and assume the “other” refers to the muscle. It never does.

Four options fill that 5th slot.

The 6th character then picks the side. Use 1 for the right arm, 2 for the left arm, and 9 when the record never says.

So S46.191A has no laterality problem at all. A query on this code is almost always about injury type or encounter phase.

Break the code down, character by character

Each character narrows the code by one decision. Walking down the tree is the fastest way to prove you landed on the right one.

Only the full seven characters bill. S46.19 and S46.191 are stems, so a claim carrying either one rejects as an invalid code.

If you prefer to browse the tree, the AAPC ICD-10-CM code lookup lists the same branches with their index references.

The 7th character A tracks active treatment, not visit number

A stands for initial encounter, and initial encounter means active treatment. Visit number has nothing to do with it. Someone on their fourth appointment still codes to A while the surgeon actively treats the injury.

Every Chapter 19 injury code needs one of these three characters. A tendon sheath injection reported with CPT 20550 is still active treatment, so it takes A as well.

When to switch from A to D

Switch once the plan of care shifts from treating the injury to watching it heal. A wound check, a range-of-motion review, or a therapy session under an established plan all take the D character.

Carrying A through eight weeks of therapy is what costs practices money. The payer usually flags it weeks later, long after anyone remembers the visit.

When sequela (S) applies

Sequela coding needs two codes and a specific order. List the residual condition first, then S46.191S for the injury that caused it.

Chronic weakness or a stiff shoulder months after the original event fits this pattern. Never add A or D alongside S for the same injury.

Codes coders reach for by mistake

Most mix-ups come from the neighbors below. Each one differs from S46.191A by the structure, the injury type, or the side. All are initial-encounter codes, so you can compare them line by line.

S46.8 is where the catch-all for other muscles at this level lives. Reading S46.191A as a spare bucket for shoulder soft tissue is the most common error on this code.

Cuff problems are the other frequent detour. A positive Neer’s test points at impingement rather than the long head, and an atraumatic complete cuff tear codes to M75.121.

The ICD-9 crosswalk is 959.2, and only approximate

CMS General Equivalence Mappings, or GEMs, convert S46.191A to ICD-9-CM 959.2, shoulder and upper arm injury.

The mapping loses almost everything useful. ICD-9 959.2 covered any unspecified injury in the region, so it carries no structure, no side, and no encounter phase.

Legacy registries and retrospective research still ask for the ICD-9 code. Claims do not. Any date of service from October 1, 2015 onward needs the ICD-10-CM code instead. Check the GEMs files published by CMS if a payer or registry asks you to map in either direction.

What the note must say before you bill S46.191A

Seven checks decide whether this code holds up under review. Miss one and the claim either drops to an unspecified sibling or comes back for more information.

• Structure: the note names the long head of the biceps. “Biceps tendon” alone leaves a coder choosing between S46.1 and S46.2.
• Injury type: the record describes a named injury that is neither a strain nor a laceration.
• Side: the note says right arm. The 6th character is already committed, so a left-sided note sends you to S46.192A.
• Encounter phase: the chart shows active treatment on this date rather than routine follow-up.
• Mechanism: how the injury happened. Chapter 19 asks for a secondary external cause code from Chapter 20.
• Open wound: S46 carries a Code Also note for an associated open wound, which lives in the S41 category. A right shoulder laceration with a foreign body, for example, is S41.021A.
• Retained foreign body: add a code from Z18 when something is still in the wound.

These details are cheap to capture at the point of care and expensive to chase later. A coder who has to email a provider three days after the visit is already working against the clock. Good clinical record keeping puts the answer inside the chart instead.

Which practices report this code

Orthopedics, physical therapy, sports medicine, emergency departments, and workers’ comp billing account for nearly all S46.191A claims. The code stays the same across them. What changes is how quickly the encounter phase moves on.

Workers’ comp deserves its own note. State boards set their own billing rules, and several ask for external cause codes covering the mechanism and the place of injury. No blanket statement covers them all, so confirm with the applicable board or payer.

Therapy and sports practices carry the other risk, because they see the same shoulder many times. Physical therapy software and sports medicine workflows keep the visit history next to the note, which makes the phase easy to check.

How Pabau keeps the code and the note in one record

Plenty of practices split this job across two screens. The note sits in the chart, the code sits in a lookup tab, and someone re-types the result into the claim. Every re-key is another chance for S46.191A to arrive as S46.199A.

Practice management software like Pabau keeps the reference inside the chart. Its ICD-10-CM and CPT libraries hold more than 20,000 codes and refresh with each official release. A coder can search S46.1 without leaving the encounter, and codes recorded on the patient record then seed the claim form.

Pabau’s claims management checks that the fields your payer requires are complete before submission unlocks. It will not choose your 7th character for you. That call stays with the coder, which is why the wording in the note matters more than any software setting.

Documentation is the other half of the problem. Pabau Scribe, our AI scribe, drafts the consultation note while the appointment happens.

When a provider says “partial tear of the right long head of biceps”, that phrase reaches the record instead of someone’s memory. The coder then has the structure, the side, and the phase in front of them.

Keep ICD-10 coding and claims in one record

Pabau puts a refreshed ICD-10-CM library inside the patient record. Codes you document seed the claim form, and payer-required fields are checked before you submit.

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Conclusion

S46.191A rewards a note that names the structure, the side, and the phase of care. Get those three right and the claim rarely comes back.

Two habits keep it clean. Read the 5th character as the injury type and the 6th as the side. Then confirm the visit is still active treatment before you commit to the A character. When the note names another muscle, move to the S46.8 family instead.

Pabau keeps the code library and the clinical note in the same record, which makes both checks quick. Book a demo to see how your team could code shoulder injuries and bill them from one place.

Continue your research

Coding another injury in the same block? S49.109P covers a distal humerus growth plate malunion.

Need the sequela side of the same chapter? S43.312S shows how to sequence a residual condition ahead of the injury code.

Billing the shoulder surgery that follows? 23462 walks through a capsule repair claim, with RVUs and modifiers.

Working at the same anatomical level? 24076 covers a subfascial soft tissue excision in the upper arm.

Tightening up your billing routine? Medical billing compliance covers the checks that keep audits quiet.

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