2026 ICD-10-CM Diagnosis Code S31.001DUnspecified open wound of lower back and pelvis with penetration into retroperitoneum, subsequent encounter

ICD-10-CM Codes›S00–T88›S30-S39›S31

ICD-10-CM S31.001D
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S31.001D is a billable ICD-10-CM diagnosis code for unspecified open wound of lower back and pelvis with penetration into retroperitoneum, subsequent encounter. The 7th character D marks it as a subsequent encounter code, used during routine care in the healing or recovery phase. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 949 through 950. The code is exempt from POA reporting. Coders also document this condition as open dislocation of lumbar vertebra. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Open wounds of trunk, subsequent encounter.

Code Identity

ICD-10-CM Code
S31.001D
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified open wound of lower back and pelvis with penetration into retroperitoneum, subsequent encounter
Short Description
Unsp opn wnd low back and pelvis w penet retroperiton, subs
Parent Code
S31.001
Unspecified open wound of lower back and pelvis with penetration into retroperitoneum

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
CategoryS31Open wound of abdomen, lower back, pelvis and external genitals
This CodeS31.001DUnspecified open wound of lower back and pelvis with penetration into retroperitoneum, subsequent encounter

Present on Admission (POA)Billing

S31.001D is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Open dislocation of lumbar vertebra
  • Open division lumbosacral ligament
  • Open spinal dislocation with anterior lumbar cord lesion
  • Open spinal dislocation with complete lumbar cord lesion
  • Posterior cord syndrome of lumbar spinal cord
  • Posterior cord syndrome of lumbar spinal cord due to open dislocation of lumbar spine

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Open wound of abdomen, lower back, pelvis and external genitals (S31). 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 INJ050
Open wounds of trunk, subsequent 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 S31.001D to ICD-9-CMHistory

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

ICD-9-CM
V58.89 Other specfied aftercare
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 S31.001DOverview

Is S31.001D a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified open wound of lower back and pelvis with penetration into retroperitoneum, subsequent encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character D in S31.001D mean?

The final character D marks a subsequent encounter: use it for routine care while the unspecified open wound of lower back and pelvis with penetration into retroperitoneum is healing, after active treatment has ended.

What MS-DRG does S31.001D group to?

When unspecified open wound of lower back and pelvis with penetration into retroperitoneum, subsequent encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 949, 950, with relative weights from 0.6277 to 1.1897 depending on complications. Higher weights mean higher Medicare reimbursement.

Is S31.001D exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for unspecified open wound of lower back and pelvis with penetration into retroperitoneum, subsequent encounter on inpatient claims.

What is the ICD-9 equivalent of S31.001D?

Under the General Equivalence Mappings, unspecified open wound of lower back and pelvis with penetration into retroperitoneum, subsequent encounter converts to ICD-9-CM V58.89 (other specfied aftercare). 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.