ICD-10 Code K65.0 – Generalized (acute) peritonitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K65.0 – Generalized (acute) peritonitis
What it is
K65.0 identifies acute inflammation of the peritoneum that is widespread rather than limited to one area. It usually reflects a serious intra-abdominal infection or contamination requiring prompt evaluation.
Clinical signs
Clinical features vary; refer to documentation. Common findings include diffuse abdominal pain, tenderness, guarding, rigidity, and signs of systemic illness such as fever or ileus.
When to use this code
Use K65.0 when the record clearly documents generalized or diffuse acute peritonitis. It may apply when the provider identifies peritoneal infection after perforation, abdominal surgery, or another intra-abdominal source. Code only when the condition is stated, not merely suspected.
Do not use for
Do not use this code for localized peritonitis, chronic peritonitis, or postoperative abdominal pain without documented peritoneal inflammation. Check documentation if the note only describes an abdominal infection without specifying generalized acute peritonitis.
Coding tip
Look for the provider’s exact wording, because “peritonitis” alone may not confirm the generalized acute form.