2027 ICD-10-CM Diagnosis Code S39.002AUnspecified injury of muscle, fascia and tendon of lower back, initial encounter

ICD-10-CM Codes›S00–T88›S30-S39›S39

ICD-10-CM S39.002A
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

S39.002A is a billable ICD-10-CM diagnosis code for unspecified injury of muscle, fascia and tendon of lower back, 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 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 913 through 914, 963 through 965. Coders also document this condition as injury of fascia of lower back. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury to nerves, muscles and tendons, initial encounter.

Code Identity

ICD-10-CM Code
S39.002A
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified injury of muscle, fascia and tendon of lower back, initial encounter
Short Description
Unsp injury of muscle, fascia and tendon of lower back, init
Parent Code
S39.002
Unspecified injury of muscle, fascia and tendon of lower back

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS30-S39Injuries to the abdomen, lower back, lumbar spine, pelvis and external genitals
CategoryS39Other and unspecified injuries of abdomen, lower back, pelvis and external genitals
This CodeS39.002AUnspecified injury of muscle, fascia and tendon of lower back, initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Injury of fascia of lower back
  • Injury of muscle and tendon of abdomen, lower back and pelvis
  • Injury of muscle of lower back
  • Injury of tendon of lower back

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Other and unspecified injuries of abdomen, lower back, pelvis and external genitals (S39). 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 2027, published by CMS and the National Center for Health Statistics.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to S39.002A: its own notes plus those printed at S39, block S30-S39, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Block S30-S39 Injuries to the abdomen, lower back, lumbar spine, pelvis and external genitals applies to 2,679 codes
  • injuries to the abdominal wall
  • injuries to the anus
  • injuries to the buttock
  • injuries to the external genitalia
  • injuries to the flank
  • injuries to the groin

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From S39 Other and unspecified injuries of abdomen, lower back, pelvis and external genitals applies to 63 codes
  • sprain of joints and ligaments of lumbar spine and pelvis (S33.-)
From Block S30-S39 Injuries to the abdomen, lower back, lumbar spine, pelvis and external genitals applies to 2,679 codes
  • burns and corrosions (T20-T32)
  • effects of foreign body in anus and rectum (T18.5)
  • effects of foreign body in genitourinary tract (T19.-)
  • effects of foreign body in stomach, small intestine and colon (T18.2-T18.4)
  • frostbite (T33-T34)
  • insect bite or sting, venomous (T63.4)
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • code to identify any retained foreign body, if applicable (Z18.-)

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From S39 Other and unspecified injuries of abdomen, lower back, pelvis and external genitals applies to 63 codes
  • any associated open wound (S31.-)

Notes

General instructions on how these codes are used.

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • 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.

7th Character

Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.

From S39 Other and unspecified injuries of abdomen, lower back, pelvis and external genitals applies to 63 codes
  • The appropriate 7th character is to be added to each code from category S39
Values for category S39 Encounter: Initial, Subsequent, Sequela
  • Ainitial encounter this code
  • Dsubsequent encounter
  • Ssequela

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Clinical ClassificationClinical

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

CCSR INJ025
Injury to nerves, muscles and tendons, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

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 S39.002A to ICD-9-CMHistory

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

ICD-9-CM
959.19 Trunk injury-sites NEC
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About S39.002AOverview

Is S39.002A a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified injury of muscle, fascia and tendon of lower back, initial encounter on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What does the 7th character A in S39.002A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for unspecified injury of muscle, fascia and tendon of lower back, such as an emergency visit or first evaluation.

What MS-DRG does S39.002A group to?

When unspecified injury of muscle, fascia and tendon of lower back, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 964, 965, 914, 913, 963, with relative weights from 0.9281 to 2.6361 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of S39.002A?

Under the General Equivalence Mappings, unspecified injury of muscle, fascia and tendon of lower back, initial encounter converts to ICD-9-CM 959.19 (trunk injury-sites NEC). The mapping is approximate, so confirm the match fits the documentation.