ICD-10 Code K65.2 – Spontaneous bacterial peritonitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K65.2 – Spontaneous bacterial peritonitis
What it is
K65.2 identifies spontaneous bacterial peritonitis, an infection of the peritoneal fluid and lining that occurs without an obvious surgical source. It is most often associated with ascites, especially in patients with chronic liver disease.
Clinical signs
Typical findings include abdominal pain, tenderness, fever, worsening ascites, or unexplained mental status changes. Clinical features vary; refer to documentation, and confirm that the infection is spontaneous rather than due to a perforation or procedure.
When to use this code
Use K65.2 when the record clearly documents spontaneous bacterial peritonitis or SBP as the diagnosis. It may be supported by provider assessment, ascitic fluid evaluation, or treatment notes, but you should code only what is documented. If the chart suggests secondary peritonitis or another abdominal source, do not assign this code.
Do not use for
Do not use this code for peritonitis with a known surgical, traumatic, or perforation-related cause. If documentation is unclear, check documentation and avoid assuming SBP.
Coding tip
Code K65.2 only when the provider explicitly links peritonitis to a spontaneous, non-surgical source.