S42.473B
Displaced transcondylar fracture of unspecified humerus, initial encounter for open fracture
S42.473B (also written S42473B) is a billable ICD-10-CM diagnosis code for displaced transcondylar fracture of unspecified humerus, initial encounter for open fracture. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 1398 codes in category S42 (Fracture of shoulder and upper arm). Its 7th character, B, means initial encounter for open fracture. Its coding notes include a Use additional code instruction, 1 Excludes1 entry and 9 Excludes2 entries.
7th character
Category S42 requires a 7th character.
Guidelines tips
From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.
A fracture not stated as open or closed is coded closed, and one not stated as displaced or not displaced is coded displaced. Nonunion and malunion have their own 7th characters.
The 7th character depends on whether the patient is in active treatment, not on who sees the patient. An aftercare Z code is not used for injury aftercare.
Each injury gets its own code unless a combination code exists, with the most serious injury first. Superficial injuries at the same site as a more severe injury are not coded. Injuries during medical care are coded as complications.
Use additional code
Add the listed code as a secondary code, if known.
Also from chapter/block level (1 note)
- code to identify any retained foreign body, if applicable (Z18.-)
Excludes1
Not coded here. The listed conditions generally should not be reported together.
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
- periprosthetic fracture around internal prosthetic shoulder joint (M97.3)
Also from chapter/block level (6 notes)
- birth trauma (P10-P15)
- obstetric trauma (O70-O71)
Care settings
How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.
Hospital MCC
Counts as a major complication or comorbidity (MCC) when reported as a secondary diagnosis on an inpatient claim. It does not count when the principal diagnosis is one of the 250 codes in its exclusion list. Some MS-DRGs also ignore a CC or MCC that defines the DRG.
Source: CMS MS-DRG Definitions Manual v44, effective October 1, 2026, Appendix CHAC
On the CMS list of hospital-acquired conditions (HAC 05: Falls and Trauma). When the claim reports it with a present-on-admission (POA) indicator of N (not present) or U (documentation insufficient), CMS does not pay the CC or MCC DRG for it. A POA of Y (present) or W (clinically undetermined) is paid normally.
Source: CMS MS-DRG Definitions Manual v44, effective October 1, 2026, Appendix I; CMS Hospital-Acquired Conditions (HAC) Coding page, POA indicator payment tableIncludes
Further defines or gives examples of the content of the category.
Also from chapter/block level (2 notes)
- injuries of axilla
- injuries of scapular region
Notes
- A fracture not indicated as displaced or nondisplaced should be coded to displaced
- A fracture not indicated as open or closed should be coded to closed
Also from chapter/block level (2 notes)
- Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
- The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.