ICD-10 code S45.019A: Laceration of axillary artery, unspecified side

Key takeaways

S45.019A is the billable ICD-10-CM code for laceration of the axillary artery, unspecified side, initial encounter.

The code has been valid for HIPAA-covered transactions since October 1, 2025, the start of FY2026.

The 7th character A applies only during active treatment, while D covers follow-up and S covers sequela.

Assign S45.019A only when the operative or injury report genuinely does not name the right or left side.

Practice management software like Pabau keeps ICD-10-CM assignments and the notes that support them in one record.

ICD-10 code S45.019A is the billable code for laceration of the axillary artery, unspecified side, initial encounter. It sits in the S45 block, which covers injury of blood vessels at shoulder and upper arm level. The code is valid for HIPAA-covered transactions under the FY2026 ICD-10-CM code set.

Below you will find the character-by-character breakdown, the three 7th character options, the laterality siblings, MS-DRG mapping, and the POA indicator. The last section covers what the operative note must say before the code holds up in an audit.

ICD-10 code S45.019A: Code details at a glance

The table below summarizes ICD-10 code S45.019A for quick reference during coding or documentation review.

What does S45.019A mean? Breaking down the code

S45.019A reads as a lacerated axillary artery, side not documented, treated during an initial encounter. Each character carries one piece of that meaning, and reading them in order prevents laterality and encounter-type errors. Accurate HIPAA-compliant documentation starts with getting each character right.

The 6th character is where many submissions go wrong. A 9 belongs there only when the operative note, trauma report, or physician documentation cannot confirm right or left. Using 9 as a shortcut when laterality is documented invites payer scrutiny and denials.

7th character encounter type options for S45.019

S45.019 without a 7th character is not billable. The 7th character makes it submittable, and three options exist, each tied to the patient’s care stage. This convention comes from the CMS ICD-10-CM guidelines.

Initial encounter (A) does not mean the patient’s first visit to any provider. It means the patient is still in the active treatment phase. A second surgery at another facility for the same laceration still uses A, not D.

Laterality siblings for axillary artery laceration

S45.019A sits inside a set of laterality siblings. When the record specifies the injured side, the laterality-specific code takes precedence over the unspecified variant. The same rule governs shoulder-region fracture codes such as S42.442K.

Parent code hierarchy

The full hierarchical path to S45.019A, confirmed against the CDC ICD-10-CM lookup tool, appears below.

• S00-T88: Injury, Poisoning and Certain Other Consequences of External Causes
• S40-S49: Injuries to the shoulder and upper arm
• S45: Injury of blood vessels at shoulder and upper arm level
• S45.0: Injury of axillary artery
• S45.01: Laceration of axillary artery
• S45.019: Laceration of axillary artery, unspecified side
• S45.019A: Laceration of axillary artery, unspecified side, initial encounter (billable)

MS-DRG mapping for S45.019A

For inpatient admissions, S45.019A groups to a Medicare Severity Diagnosis Related Group, or MS-DRG. The assignment depends on whether a qualifying operating room procedure took place during the same admission.

CMS updates MS-DRG assignments every year. Check the current mapping in the CMS MS-DRG Definitions Manual for the applicable fiscal year before finalizing an inpatient claim.

Present on admission (POA) indicator for S45.019A

The POA indicator tells the payer whether the condition existed when the patient was admitted. CMS requires it for diagnoses reported on inpatient claims. For S45.019A it is usually Y for an acute traumatic injury, and N for a laceration caused during a hospital procedure.

POA indicators feed quality metrics and hospital-acquired condition payment adjustments under CMS rules. Accurate assignment protects reimbursement and lowers audit risk. Coders working with EHR integration benefit from systems that flag the POA field at code entry.

Clinical context: axillary artery lacerations

The axillary artery runs from the outer border of the first rib to the lower border of the teres major muscle. It supplies the shoulder and upper arm. Lacerations arise most often from penetrating trauma to the axilla, or from iatrogenic injury during shoulder surgery and vascular access.

Presentation typically includes rapid hematoma formation, a diminished radial pulse, and signs of upper-limb ischemia. Intraoperative identification is common in orthopedic and thoracic cases. The same operative record often supports an anesthesia claim under CPT code 01650.

The anatomical detail also settles the parent category. S45 covers blood vessel injury at this level, while S47 covers crushing injury of the shoulder and upper arm.

• Penetrating trauma: gunshot wounds, stab wounds to the axilla or shoulder region
• Iatrogenic injury: shoulder arthroplasty, subpectoral biceps tenodesis, or central line placement complications
• Blunt trauma: anterior shoulder dislocation with vascular compromise (less common)

Elective shoulder work is where the iatrogenic version shows up, so orthopedic and sports medicine practices should expect to code it occasionally. Documentation from those cases is usually detailed enough to support a laterality-specific sibling.

When S45.019A is assigned in a trauma context, ICD-10-CM guidelines require an external cause code from V00-Y99 to identify the mechanism. That code is reported as an additional diagnosis, never as the principal one. Clinical notes in the patient record should state mechanism, anatomical site, and surgical findings.

ICD-10-CM coding guidelines for S45.019A

The ICD-10-CM official guidelines set specific rules for injury codes in the S00-T88 range. Two triggers account for most S45.019A denials. One is unspecified laterality used too readily, and the other is the wrong 7th character. The same character logic runs across the injury chapter, including sequela codes such as S42.032S.

• Laterality rule: Use the unspecified code (6th character 9) only when the medical record genuinely lacks laterality information. Query the physician first if the documentation is ambiguous.
• Encounter type sequencing: The 7th character reflects the care phase rather than the visit count. Active surgical treatment = A. Routine post-surgical wound checks = D. Complications from the healed laceration = S.
• External cause codes: Sequence an external cause code as an additional code on a trauma admission. Cover mechanism of injury, place of occurrence, and activity.
• Principal diagnosis: Assign S45.019A as the principal diagnosis when a patient is admitted specifically for the axillary artery laceration. Sequence associated injuries as additional codes.
• Combination coding: If an open wound of the shoulder is documented alongside the artery laceration, both codes may be assigned. Check the instructional notes in the tabular list first.

Documentation requirements for accurate coding

The code assignment only holds if the record supports it. For S45.019A, the operative or emergency department note should document all of the following.

• Anatomical confirmation: explicit identification of the axillary artery as the injured vessel, not “shoulder vasculature” or “brachial artery”
• Injury type: use of the word “laceration”, as distinct from contusion, rupture, or pseudoaneurysm
• Laterality: right side, left side, or a clinician attestation that the side could not be determined
• Encounter context: whether treatment is active, ongoing, or addressing a sequela
• Mechanism of injury: enough detail to support an external cause code, such as blunt trauma, a penetrating wound, or an operative complication

When documentation is incomplete, send a physician query rather than assign S45.019A on assumption. Incomplete medical forms are the main driver of unspecified-code use, which lowers claim specificity. Practices using patient data security tools can build the query step into their documentation workflow.

Approximate synonyms for S45.019A

Clinical notes often describe this injury in language that differs from the official ICD-10-CM wording. These approximate synonyms map to S45.019A in standard coding references and are useful during index lookups. Practice management software that indexes synonyms cuts down on manual code book searches.

• Axillary artery laceration, unspecified side
• Laceration of right or left axillary artery, side unspecified (initial visit)
• Cut wound of axillary artery
• Traumatic laceration of axillary artery
• Iatrogenic laceration of axillary artery, unspecified laterality

These synonyms appear in the ICD-10-CM alphabetic index under “Laceration, artery, axillary.” Coders cross-referencing the WHO ICD-10 browser will find the international classification maps closely to the US clinical modification. The CM version adds laterality specificity that the WHO base does not carry.

How Pabau keeps coding and documentation in one record

Coding a trauma admission usually means moving between three systems. The operative note lives in one, the coded diagnosis in a second, and the claim status in a third. Laterality and encounter details go missing in the handoffs.

Practice management software like Pabau holds all three in the same patient record. Coders open the note, assign the ICD-10-CM code against it, and submit the claim without leaving the file. Claims management then tracks what the payer did with it.

That matters most for the laterality decision this code turns on. When the operative note sits beside the code field, a coder can check for right or left before defaulting to 9. Surgical teams in plastic surgery practices get the same audit trail for reconstructive repairs.

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Conclusion

Three decisions settle this code before the claim goes out. Confirm the injury is a laceration rather than a rupture or contusion. Check whether the record names a side. Then pick the 7th character that matches the care phase.

S45.019A is the right answer only when the side is genuinely unknown at the time of coding. Query the physician before you settle for it, because a laterality-specific sibling carries more weight with a payer.

Book a demo to see how Pabau keeps coded diagnoses, operative notes, and claim status in one auditable record.

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