ICD10BillableValid for clinical use

ICD-10 Code K65.9: Peritonitis, unspecified

K65.9 is a billable ICD-10 diagnosis code used to classify Peritonitis, unspecified in medical records and claims. You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records. ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Diseases of the digestive system (K00-K95).

Reviewed by HealthAssure Clinical TeamUpdated 26 May 2026

What is this code?

ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Diseases of the digestive system (K00-K95).

When is it used?

  • May be used when a clinician documents peritonitis, unspecified in a patient's medical record.
  • May appear in hospital records, claims, referrals, and clinical documentation.
  • This code can be used as a clinically usable diagnosis entry in standardized coding workflows.

What it does not mean

  • A code alone does not explain severity, treatment plan, or outcome.
  • A medical code should not be treated as a substitute for a doctor's diagnosis or advice.

Code hierarchy

chapter
11Diseases of the digestive system (K00-K95)
block
K65-K68Diseases of peritoneum and retroperitoneum
category
K65Peritonitis
currentK65

Official coding notes

Inclusion terms
  • Bacterial peritonitis NOS

Where you may see this code

You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.

Related specialists

GastroenterologistGeneral Physician

Coverage-related procedures and services

Coding guidelines

Compatibility

Legacy and official ICD code match exactly.
Legacy codes
K65.9

Common synonyms

Peritonitis, unspecifiedPeritonitis

Frequently asked questions

Code details

CodeK65.9
SystemICD10
Display namePeritonitis, unspecified
ChapterDiseases of the digestive system (K00-K95)
BlockDiseases of peritoneum and retroperitoneum

Flags

BillableYes
Valid clinical useYes

Source

SourceICD-10
Version2026-annual
Releaseannual
Year2026

Index terms

Matched terms
Fistula(cutaneous)HemoperitoneumPeritonitis(adhesive) (bacterial) (fibrinous) (hemorrhagic) (idiopathic) (localized) (perforative) (primary) (with adhesions) (with effusion)

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.

ICD-10 Code K65.9 for Peritonitis, unspecified | HealthAssure