• Clinical science



Peritonitis is an inflammation of the peritoneum that is often caused by a bacterial infection. Based on the etiology, peritonitis may be classified as primary or secondary. Primary peritonitis usually occurs in patients with underlying ascites, whereas secondary peritonitis affects those with a preexisting acute abdominal disease. Patients typically present with severe abdominal pain and guarding, as well as nausea and vomiting. In most cases, peritonitis constitutes a surgical emergency. Diagnosis is established based on the clinical presentation, laboratory tests, imaging, and peritoneal fluid analysis. Treatment includes administration of antibiotics as well as surgical interventions. Peritonitis may be further complicated by ileus, sepsis, or abdominal compartment syndrome.


Primary peritonitis (spontaneous bacterial peritonitis, or SBP)

Secondary peritonitis (secondary bacterial peritonitis); more common

Further causes

  • Peritonitis in immunosuppressed (mainly HIV-positive) patients
  • Chemical peritonitis: nonbacterial, caused by irritants such as blood, bile, urine, or barium contrast in the peritoneal cavity


Clinical features

Peritonitis is considered a surgical emergency, as it may cause sepsis with shock and organ failure!



The diagnosis of peritonitis is based primarily on physical manifestations. Peritoneal fluid analysis confirms the diagnosis, while imaging tests may help to identify the underlying disease and exclude differential diagnoses.


Differential diagnoses

In certain conditions, patients show symptoms of peritonitis, although actual inflammation of the peritoneum is absent.

The differential diagnoses listed here are not exhaustive.


Primary peritonitis [2]

Secondary peritonitis




We list the most important complications. The selection is not exhaustive.