2026 ICD-10-CM Diagnosis Code S33.100ASubluxation of unspecified lumbar vertebra, initial encounter

ICD-10-CM Codes›S00–T88›S30-S39›S33

ICD-10-CM S33.100A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S33.100A is a billable ICD-10-CM diagnosis code for subluxation of unspecified lumbar vertebra, 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 551 through 552, 963 through 965. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Dislocations, initial encounter.

Code Identity

ICD-10-CM Code
S33.100A
Billable Status
Yes — Valid for Submission
Code Describes
Subluxation of unspecified lumbar vertebra, initial encounter
Short Description
Subluxation of unspecified lumbar vertebra, init encntr
Parent Code
S33.100
Subluxation of unspecified lumbar vertebra

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
CategoryS33Dislocation and sprain of joints and ligaments of lumbar spine and pelvis
This CodeS33.100ASubluxation of unspecified lumbar vertebra, initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Central cord syndrome of lumbar spinal cord due to closed spinal dislocation
  • Central cord syndrome of lumbar spinal cord due to closed spinal subluxation
  • Central cord syndrome of lumbar spinal cord due to open spinal dislocation
  • Central cord syndrome of lumbar spinal cord due to open spinal subluxation
  • Central cord syndrome of lumbar spinal cord due to traumatic injury
  • Closed spinal dislocation with cauda equina lesion
  • Closed spinal dislocation with complete lumbar cord lesion
  • Closed spinal subluxation with anterior lumbar cord lesion
  • Closed spinal subluxation with cauda equina lesion
  • Closed spinal subluxation with complete lumbar cord lesion
  • Closed subluxation lumbar spine
  • Closed traumatic dislocation of lumbar vertebra
  • Open dislocation of lumbar vertebra
  • Open spinal dislocation with anterior lumbar cord lesion
  • Open spinal dislocation with cauda equina lesion
  • Open spinal dislocation with complete lumbar cord lesion
  • Open spinal subluxation with anterior lumbar cord lesion
  • Open spinal subluxation with cauda equina lesion
  • Open spinal subluxation with complete lumbar cord lesion
  • Open subluxation lumbar spine
  • Posterior cord syndrome of lumbar spinal cord
  • Posterior cord syndrome of lumbar spinal cord due to open dislocation of lumbar spine
  • Posterior cord syndrome of lumbar spinal cord due to open subluxation of lumbar spine
  • Posterior cord syndrome of lumbar spine due to closed dislocation of lumbar spine
  • Posterior cord syndrome of lumbar spine due to closed subluxation of lumbar spine
  • Spinal subluxation with cauda equina lesion
  • Spinal subluxation with lumbar cord lesion
  • Subluxation of joint of lumbar spine

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Dislocation and sprain of joints and ligaments of lumbar spine and pelvis (S33). 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 INJ007
Dislocations, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Dislocations

Dislocations are joint injuries that force the ends of your bones out of position. The cause is often a fall or a blow, sometimes from playing a contact sport. You can dislocate your ankles, knees, shoulders, hips, elbows and jaw. You can also dislocate your finger and toe joints.

Read the full article at MedlinePlus

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

Convert S33.100A to ICD-9-CMHistory

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

ICD-9-CM
839.20 Dislocat lumbar vert-cl
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 S33.100AOverview

Is S33.100A (Subluxation of unspecified lumbar vertebra) a billable code?

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

What does the 7th character A in S33.100A mean?

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

What MS-DRG does S33.100A group to?

When subluxation of unspecified lumbar vertebra, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 551, 552, 963, 964, 965, with relative weights from 0.9405 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of S33.100A?

Under the General Equivalence Mappings, subluxation of unspecified lumbar vertebra, initial encounter converts to ICD-9-CM 839.20 (dislocat lumbar vert-cl). 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.