ICD code S52.265M – Nondisplaced segmental fracture of left ulnar shaft with nonunion (open type I or II)

Key takeaways

S52.265M codes a nondisplaced segmental fracture of the left ulnar shaft with nonunion, at a follow-up visit after an open type I or II injury.

The 7th character M carries two facts at once: The fracture was open, graded Gustilo-Anderson type I or II, and the provider has documented nonunion.

Nonunion after a type IIIA, IIIB or IIIC open fracture codes to S52.265N, and nonunion of a closed fracture codes to S52.265K.

The record must state segmental, nondisplaced and left arm, because a fracture with no displacement status documented defaults to displaced (S52.262M).

Practice management software like Pabau keeps the open fracture grade and the nonunion note in one patient record, so the claim matches the chart.

ICD-10 code S52.265M: Definition and billable status

ICD-10 code S52.265M is a billable 7-character code in category S52, fracture of forearm. It describes a left ulnar shaft fracture with two separate fracture lines and an open wound at injury. The provider has documented that it failed to unite.

The code is reported at subsequent encounters only. Under the ICD-10-CM Official Guidelines for Coding and Reporting, a traumatic fracture keeps its acute fracture code through follow-up care, with a subsequent-encounter 7th character. Aftercare Z codes are not used for traumatic fractures.

What S52.265M covers: Breaking down the code

Each character narrows the diagnosis. Change one and the code describes a different bone, side, fracture pattern or stage of healing.

What a segmental ulnar shaft fracture is

A segmental fracture has two separate fracture lines in the same bone. That leaves a free segment of shaft between them, which can lose part of its blood supply. It is one reason segmental fractures are watched closely for nonunion.

Nondisplaced means the fragments stayed in alignment. A comminuted fracture, with several fragments rather than one clean segment, codes to S52.25- instead. Always confirm the pattern against the CDC/NCHS ICD-10-CM tabular list for the current fiscal year.

Understanding the 7th character M: Open fracture type I or II with nonunion

Category S52 uses an extended set of 16 7th characters. Each one combines three facts: The encounter phase, whether the fracture was open and how it was graded, and the healing status.

M sits where an open type I or II fracture meets nonunion. The open designation stays with the fracture for its whole course. A patient whose wound closed months ago still codes to M, not K, at a nonunion visit. The grid below maps the 12 follow-up characters by open grade and healing status.

Gustilo-Anderson grade and why it decides M over K or N

ICD-10-CM bases the open fracture 7th characters for the forearm, femur and lower leg on the Gustilo-Anderson classification. Type I is a clean wound under 1 cm. Type II is a wound over 1 cm without extensive soft-tissue damage.

Type III injuries carry extensive soft-tissue damage and split into IIIA, IIIB and IIIC. Any of those grades moves a nonunion from M to N. The grade comes from the initial treatment record, usually the emergency or operative note.

If no grade appears anywhere in the record, query the treating surgeon. Do not settle the choice between M and N by assumption.

The line between delayed healing (H) and nonunion (M) is a clinical judgment. Code nonunion only when the provider documents it. Elapsed weeks or a coder’s own reading of the X-ray never turn H into M.

Laterality and commonly confused codes

The 6th character of a segmental ulnar shaft fracture carries both displacement and side. All six options share the M 7th character, so they are easy to swap by accident.

Reserve S52.266M for a record that omits the side, which is rare at a nonunion visit. If the arm is in the imaging report but not the note, ask the provider to confirm it.

Includes, excludes, and official coding notes

What the code includes

• Nonunion of a nondisplaced segmental fracture of the left ulnar shaft, where the original fracture was open, Gustilo-Anderson type I or II
• Follow-up visits after initial treatment, such as debridement, fixation or casting, once the provider documents nonunion
• Encounters to plan or monitor nonunion care, including bone stimulation and surgical repair

What the code excludes

• Physeal (growth plate) fractures of the radius or ulna in children, which code to S59
• Fractures at the wrist and hand level, which code to S62.-
• Traumatic amputation of the forearm, which codes to S58.-
• Periprosthetic fracture around an internal prosthetic elbow joint, which codes to M97.4
• Radius fractures, including distal radius fractures (S52.5-), which have their own subcategories
• Pathological and stress fractures of the ulna, which code to M84.-
• The first visit for the fracture, which takes S52.265B for an open type I or II injury

Two default rules in the S52 notes matter here. A fracture not documented as open or closed codes to closed. A fracture not documented as displaced or nondisplaced codes to displaced.

Clinical documentation requirements for S52.265M

Every element of the code has to be traceable to the chart. A payer reviewing an S52.265M claim will look for each of these in the record.

• Open fracture grade: Gustilo-Anderson type I or II, recorded in the initial treatment or operative note. A follow-up note that restates the grade makes the link easy to audit.
• Nonunion statement: The provider’s own diagnosis of nonunion in the current note. Wording such as “slow healing” or “delayed union” supports S52.265H, not M.
• Imaging that shows no union: Forearm radiographs or CT showing persistent fracture lines without bridging bone. The provider should interpret the images in the note, not leave them in a standalone report.
• Fracture pattern: A segmental fracture of the ulnar shaft, with the fragments documented as nondisplaced.
• Laterality: Left arm, stated the same way in the note, the imaging report and the claim.
• Encounter context: The date and type of initial treatment, so the visit is clearly a subsequent encounter.

Keeping these elements in one encounter note makes an audit far simpler. Orthopedic follow-up documentation depends on a clear link between imaging, the nonunion assessment and the coded visit. Building a clean claim starts with confirming that link before the code is chosen.

CPT codes commonly paired with S52.265M

S52.265M supports the evaluation, imaging and treatment of an ulnar nonunion. The pairings below are the usual ones. Check current NCCI edits and payer policy before submission, because bundling rules change each year.

The stimulator device itself is billed separately by the supplier, under HCPCS E0747 for a noninvasive electrical unit. The how medical billing works overview covers how diagnosis and procedure codes link on a CMS-1500 claim form.

Payer requirements and prior authorization

Medicare covers noninvasive electrical bone growth stimulators for nonunion of long bone fractures under National Coverage Determination 150.2. The ulna counts as a long bone. Nonunion has to be shown by at least two sets of radiographs taken before treatment starts.

Those two sets must be at least 90 days apart. The DME osteogenesis stimulators LCD (L33796) also asks for multiple views of the fracture site in each set. A nonunion diagnosed on a single film will not meet that bar, whatever the 7th character says.

Commercial payers often require prior authorization for bone stimulation and for nonunion surgery such as 25400 or 25405. Expect a request for the imaging reports, the nonunion assessment and the original treatment record. If physical therapy follows the repair, track authorization per visit so those sessions never go out unapproved.

Pabau’s Claim.MD integration runs real-time eligibility checks (270/271) before the visit. A lapsed policy or a missing authorization then shows up while there is still time to act on it.

Common claim denial reasons for S52.265M

Most S52.265M denials trace back to one 7th character or one missing line in the chart. Match the CARC on the remittance advice to the cause before you correct or appeal.

Denial management workflows that sort denials by CARC at ERA posting cut the time between a denial and a corrected claim. The medical billing denial codes reference explains the most frequent CARC values and what each one needs for a successful appeal.

How Pabau keeps S52.265M nonunion claims clean

An S52.265M claim depends on facts recorded months apart. The open fracture grade sits in the first emergency or operative note. The nonunion diagnosis appears in a follow-up visit long after. When those notes live in different places, the coder rebuilds the history by hand and the 7th character becomes a guess.

Pabau keeps the whole injury history in one patient record, from the first visit to the nonunion follow-up. For cleaner claims management, Pabau builds each claim from the visit and its invoice. Through Claim.MD, Pabau submits CMS-1500 claims electronically, checks eligibility in real time and flags denied claims for rework.

The result is a claim your team can defend from the chart alone. Every Pabau subscription includes the full feature set, so notes, billing and reporting work from the same record.

Keep the fracture grade and the claim in step

Pabau keeps the original fracture grade, the nonunion note and the claim in one patient record. Eligibility checks through Claim.MD run before the visit, and denied claims come back flagged for rework.

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Conclusion

S52.265M is rarely miscoded because of the bone or the side. It goes wrong in the 7th character, where an open fracture grade from months ago meets a nonunion diagnosis made today. Treat both as facts to find in the record, never as assumptions to fill in.

Practices that confirm the Gustilo-Anderson grade, the nonunion statement and the imaging before submission avoid the costly records requests. Mapping your revenue cycle management end to end shows where these claims stall, so the fix can happen upstream.

Book a demo to see how Pabau keeps fracture history, claims and eligibility checks in one place for orthopedic follow-up care.

Continue your research

Need a denial management framework for your billing team? Denial management in healthcare covers CARC-based categorization, appeal timelines, and workflow automation for high-volume claim teams.

Want to understand how the Claim.MD clearinghouse integration works? Claim.MD clearinghouse explains how Pabau submits claims, checks eligibility and matches remittances through Claim.MD.

Looking for the full list of medical billing denial codes? Medical billing denial codes provides a reference for CARC values and what each one requires for a successful appeal.

Coding a displaced fracture of the same arm that was never open? ICD-10 code S52.262K covers nonunion of a displaced segmental left ulnar shaft fracture after a closed injury.

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