2026 ICD-10-CM Diagnosis Code S36.81XAInjury of peritoneum, initial encounter
S36.81XA is a billable ICD-10-CM diagnosis code for injury of peritoneum, 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 injury of peritoneum. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Internal organ injury, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Injury of peritoneum
- Injury of peritoneum without open wound into abdominal cavity
- Peritoneal foreign body
- Peritoneum injury with open wound into cavity
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.
Patient EducationClinical
Peritoneal Disorders
Your peritoneum is the tissue that lines your abdominal wall and covers most of the organs in your abdomen. A liquid, peritoneal fluid, lubricates the surface of this tissue.
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Convert S36.81XA to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S36.81XAOverview
Is S36.81XA (Injury of peritoneum) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report injury of peritoneum, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in S36.81XA mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for injury of peritoneum, such as an emergency visit or first evaluation.
What MS-DRG does S36.81XA group to?
When injury of peritoneum, 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 S36.81XA?
Under the General Equivalence Mappings, injury of peritoneum, initial encounter converts to ICD-9-CM 868.03 (peritoneum injury-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.
