2026 ICD-10-CM Diagnosis Code S51.809AUnspecified open wound of unspecified forearm, initial encounter

ICD-10-CM S51.809A

CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S51.809A is a billable ICD-10-CM diagnosis code for unspecified open wound of unspecified forearm, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 604 through 605, 963 through 965. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Open wounds to limbs, initial encounter.

Code Identity

ICD-10-CM Code

S51.809A

Billable Status

Yes — Valid for Submission

Code Describes

Unspecified open wound of unspecified forearm, initial encounter

Short Description

Unspecified open wound of unspecified forearm, init encntr

Parent Code

S51.809

Unspecified open wound of unspecified forearm

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes

SectionS50-S59Injuries to the elbow and forearm

CategoryS51Open wound of elbow and forearm

This CodeS51.809AUnspecified open wound of unspecified forearm, initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

Filter synonyms:

Barton's fracture
Colles' fracture
Dorsal Barton's fracture
Fracture dislocation of radiocarpal joint
Fracture of coronoid process of ulna
Fracture of distal end of radius and ulna
Fracture of proximal end of radius and ulna
Fracture of radial head
Fracture of radial neck
Fracture of radial styloid
Fracture of ulnar styloid
Galeazzi fracture dislocation
Glass in forearm
Injury of branch of median nerve
Injury of branch of radial nerve
Injury of branch of ulnar nerve
Injury of radial artery
Injury of radial blood vessel
Injury of ulnar artery
Injury of ulnar nerve
Lesion of sensory branch of radial nerve
Metaphyseal fracture of bone of upper limb
Monteggia's fracture
Multiple open wounds of forearm
Open Barton's fracture
Open Colles' fracture
Open dorsal Barton's fracture
Open fracture dislocation radiocarpal joint
Open fracture distal radius, intra-articular, die-punch
Open fracture of coronoid process of ulna
Open fracture of distal end of radius
Open fracture of distal end of ulna
Open fracture of forearm
Open fracture of head of radius
Open fracture of lower end of forearm
Open fracture of lower end of radius AND ulna
Open fracture of metaphysis of distal radius
Open fracture of neck of radius
Open fracture of olecranon process of ulna
Open fracture of proximal end of radius
Open fracture of proximal end of ulna
Open fracture of radius
Open fracture of radius AND ulna
Open fracture of shaft of bone of forearm
Open fracture of shaft of radius
Open fracture of shaft of ulna
Open fracture of ulna
Open fracture of ulna, lower epiphysis
Open fracture of ulna, styloid process
Open fracture of upper end of forearm
Open fracture of upper end of radius AND ulna
Open fracture olecranon, extra-articular
Open fracture olecranon, intra-articular
Open fracture proximal radius, comminuted
Open fracture proximal ulna, comminuted
Open fracture radial styloid
Open Galeazzi fracture
Open injury of sensory branch of radial nerve
Open injury, median nerve, motor branch
Open injury, radial artery
Open injury, ulnar artery
Open injury, ulnar nerve
Open injury, ulnar nerve, palmar sensory
Open Monteggia's fracture
Open multiple fractures of upper end of ulna
Open reverse Colles' fracture
Open traumatic dislocation distal radioulnar joint
Open traumatic dislocation radiocarpal joint
Open volar Barton's fracture
Open wound of forearm
Open wound of muscle of forearm
Reversed Colles' fracture
Skillern's fracture
Traumatic dislocation of radial head
Ulnar blood vessel injury
Volar Barton's fracture

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Open wound of elbow and forearm (S51). Use the following options for the applicable episode of care:

A - initial encounter
D - subsequent encounter
S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INJ012

Open wounds to limbs, initial encounter

Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

Colles' Fracture
fracture of the lower end of the radius in which the lower fragment is displaced posteriorly.
Monteggia's Fracture
fracture in the proximal half of the shaft of the ulna, with dislocation of the head of the radius.
Closed Colles' Fracture
an extra-articular traumatic break in the distal radius with dorsal displacement of the distal fragment that does not involve a break in the adjacent skin.
Colles' Fracture
an extra-articular traumatic break in the distal radius with dorsal displacement of the distal fragment.

Patient EducationClinical

Wounds and Injuries

An injury is damage to your body. It is a general term that refers to harm caused by accidents, falls, hits, weapons, and more. In the U.S., millions of people injure themselves every year. These injuries range from minor to life-threatening.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert S51.809A to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM

881.00 Open wound of forearm

Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.

FY 2017–2025No changes

FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About S51.809AOverview

Is S51.809A (Unspecified open wound of unspecified forearm) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified open wound of unspecified forearm, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in S51.809A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for unspecified open wound of unspecified forearm, such as an emergency visit or first evaluation.

What MS-DRG does S51.809A group to?

When unspecified open wound of unspecified forearm, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 604, 605, 963, 964, 965, with relative weights from 0.9160 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of S51.809A?

Under the General Equivalence Mappings, unspecified open wound of unspecified forearm, initial encounter converts to ICD-9-CM 881.00 (open wound of forearm). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.

Indicator	Meaning	CMS pays CC/MCC DRG
Y	Diagnosis was present at the time of inpatient admission	Yes
N	Diagnosis was not present at the time of admission	No
U	Documentation is insufficient to determine	No
W	Clinically undetermined	Yes
1	Unreported, exempt from POA reporting	No