2026 ICD-10-CM Diagnosis Code S36.599AOther injury of unspecified part of colon, initial encounter

ICD-10-CM Codes›S00–T88›S30-S39›S36

ICD-10-CM S36.599A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S36.599A is a billable ICD-10-CM diagnosis code for other injury of unspecified part of colon, 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 393 through 395, 963 through 965. Coders also document this condition as traumatic ulcer of large intestine. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Internal organ injury, initial encounter.

Code Identity

ICD-10-CM Code
S36.599A
Billable Status
Yes — Valid for Submission
Code Describes
Other injury of unspecified part of colon, initial encounter
Short Description
Other injury of unspecified part of colon, initial encounter
Same as the full description in the CMS dataset.
Parent Code
S36.599
Other injury of unspecified part of colon

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
CategoryS36Injury of intra-abdominal organs
This CodeS36.599AOther injury of unspecified part of colon, initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Traumatic ulcer of large intestine

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Injury of intra-abdominal organs (S36). 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 INJ010
Internal organ injury, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Colonic Diseases

Your colon, also known as the large intestine, is part of your digestive system. It's a long, hollow tube at the end of your digestive tract where your body makes and stores stool. Many disorders affect the colon's ability to work properly. Some of these include:

Read the full article at MedlinePlus

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

Convert S36.599A to ICD-9-CMHistory

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

ICD-9-CM
863.40 Colon injury NOS-closed
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 S36.599AOverview

Is S36.599A (Other injury of unspecified part of colon) a billable code?

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

What does the 7th character A in S36.599A mean?

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

What MS-DRG does S36.599A group to?

When other injury of unspecified part of colon, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 393, 394, 395, 963, 964, 965, with relative weights from 0.6490 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of S36.599A?

Under the General Equivalence Mappings, other injury of unspecified part of colon, initial encounter converts to ICD-9-CM 863.40 (colon injury NOS-closed). 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.