What is the ICD-10 code for Peritonitis?

The ICD-10-CM code for Peritonitis is K65 (fiscal year 2026). K65 is a non-billable category code — a more specific code such as K65.0 is required for claims.

What does ICD-10 code K65 mean?

K65 is the ICD-10-CM diagnosis code for Peritonitis. Peritonitis

Is K65 a billable ICD-10 code?

No, K65 is not a billable code. You may need to select a more specific code from this category.

What chapter is K65 in?

K65 is classified under Chapter 11: Diseases of the digestive system (K00-K95), Section K65-K68: Diseases of peritoneum and retroperitoneum (K65-K68).

What are the includes and excludes for K65?

Excludes1 (not coded here): acute appendicitis with generalized peritonitis (K35.2-); aseptic peritonitis (T81.6); benign paroxysmal peritonitis (E85.0).

What more specific codes exist under K65?

More specific codes under K65 include: K65.0, K65.1, K65.2, K65.3, K65.4. Select the most specific code that matches the clinical documentation.

K65 Peritonitis

⚠ Non-Billable ICD-10-CM 2026

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The ICD-10-CM code for Peritonitis is K65 (FY2026). It is a non-billable category code — select a more specific code below for claims.

Classification

Chapter: 11: Diseases of the digestive system (K00-K95)
Section: K65-K68: Diseases of peritoneum and retroperitoneum (K65-K68)
Category K65: 8 codes (7 billable)
FY2026 Status: Stable since FY2024

Excludes1

Not coded here. These conditions should NOT be coded together with K65.

acute appendicitis with generalized peritonitis (K35.2-)
aseptic peritonitis (T81.6)
benign paroxysmal peritonitis (E85.0)
chemical peritonitis (T81.6)
gonococcal peritonitis (A54.85)
neonatal peritonitis (P78.0-P78.1)
pelvic peritonitis, female (N73.3-N73.5)
periodic familial peritonitis (E85.0)
peritonitis due to talc or other foreign substance (T81.6)
peritonitis in chlamydia (A74.81)
peritonitis in diphtheria (A36.89)
peritonitis in syphilis (late) (A52.74)
peritonitis in tuberculosis (A18.31)
peritonitis with or following abortion or ectopic or molar pregnancy (O00-O07, O08.0)
peritonitis with or following appendicitis (K35.-)
puerperal peritonitis (O85)
retroperitoneal infections (K68.-)

Code Also

if applicable diverticular disease of intestine (K57.-)

Use Additional Code

code (B95-B97), to identify infectious agent, if known

Official Coding Guidelines

Chapter 11 reserved for future expansion

11. Chapter 11: Diseases of the Digestive System (K00-K95) Reserved for future guideline expansion

— ICD-10-CM Official Guidelines for Coding and Reporting, FY2026, Section I.C.11

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

K65 Peritonitis

Classification

Official Coding Guidelines

References

Related Codes

More Specific Codes

Related Codes in K65

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