Peritonitis

Peritonitis is inflammation of the peritoneum, the membrane lining the abdominal cavity and covering the abdominal organs. It is often a medical emergency because it may result from serious infection, organ perforation, or complications related to peritoneal dialysis. ^[1][2]

What is peritonitis?

Peritonitis is inflammation, usually infection-related, affecting the peritoneal lining inside the abdomen. It may develop when bacteria, fungi, digestive contents, or inflammatory fluids enter the peritoneal cavity. Common causes include a ruptured appendix, bowel perforation, perforated ulcer, severe intra-abdominal infection, and peritoneal dialysis-related infection. Because the peritoneum covers a large surface area and the abdominal cavity contains many vital organs, the condition can spread rapidly and become life-threatening. It should therefore be regarded as far more serious than ordinary stomach upset or routine abdominal pain. ^[1][2][3]

What symptoms can occur?

Severe abdominal pain is one of the most prominent symptoms. The abdomen may be tender, rigid, or markedly painful with movement. Fever, nausea, vomiting, abdominal distention, inability to pass stool or gas, weakness, and general deterioration may also occur. In dialysis-related peritonitis, cloudy dialysis fluid can be an important warning sign. As infection or inflammation worsens, low blood pressure, confusion, rapid heart rate, and signs of sepsis may develop. This is why sudden, intense abdominal pain with systemic symptoms should never be ignored. ^[1][2][4]

What causes peritonitis?

Peritonitis may be primary, secondary, or dialysis-related depending on the mechanism. The most common and clinically significant form is secondary peritonitis, in which abdominal organ disease leads to contamination of the peritoneal cavity. Bowel perforation, appendicitis, diverticulitis, ulcer perforation, pancreatitis-related complications, trauma, and postoperative leaks are among possible causes. In cirrhosis with ascites, spontaneous bacterial peritonitis is another important entity. In patients on peritoneal dialysis, catheter-related infection is also a major concern. Because treatment differs by cause, identifying the underlying mechanism is crucial. ^[1][2][5]

How is the diagnosis made?

Diagnosis relies on symptoms, examination findings, laboratory studies, and imaging. Clinicians assess the nature of the pain, abdominal guarding, fever, and signs of systemic illness. Blood tests may suggest infection or inflammation. CT imaging is often used to search for perforation, abscess, or intra-abdominal source. In spontaneous bacterial peritonitis, analysis of ascitic fluid is central. In dialysis-related cases, evaluation of peritoneal dialysis fluid is important. The purpose is not only to confirm inflammation but also to identify the source quickly, because delayed treatment can be dangerous. ^[1][2][5]

How is it treated?

Treatment usually requires urgent medical care. Antibiotics are often started promptly, but they are not always sufficient on their own. If there is perforation, abscess, ischemia, or another surgical cause, operative or procedural intervention may be necessary. In dialysis-related peritonitis, antimicrobial treatment is tailored to that context and dialysis management may need modification. Fluid support, hemodynamic monitoring, pain control, and management of sepsis may also be required. Because the stakes are high, home treatment or watchful waiting is not a safe strategy when true peritonitis is suspected. ^[1][2][4]

Why is it dangerous?

Peritonitis is dangerous because infection or contamination inside the abdomen can spread rapidly, lead to sepsis, and impair organ function. Delayed treatment can increase the risk of shock, organ failure, abscess formation, prolonged hospitalization, and death. Some patients deteriorate within hours. For that reason, peritonitis is not a condition in which severe symptoms should be observed at home while waiting for them to pass. ^[1][2][3]

When should emergency help be sought?

Emergency care is needed for severe abdominal pain, fever with abdominal tenderness, rigid abdomen, vomiting with worsening illness, faintness, low blood pressure, confusion, inability to pass stool or gas with abdominal distention, or cloudy peritoneal dialysis fluid. Anyone at risk of spontaneous bacterial peritonitis or on peritoneal dialysis should be especially cautious. Timely treatment can be critical. ^[1][2][4]

FAQ

Is peritonitis always an emergency?
In many cases, yes. Because it may progress rapidly and become life-threatening, urgent evaluation is often necessary. ^[1][2]

Can peritonitis occur without surgery?
Yes. It can occur with organ perforation, spontaneous bacterial infection in ascites, or peritoneal dialysis-related infection. ^[1][2]

What does cloudy dialysis fluid suggest?
In a patient on peritoneal dialysis, cloudy fluid can be an important warning sign of peritonitis. ^[1][4]

Can antibiotics alone always treat peritonitis?
No. If there is a perforation or another surgical source, additional intervention may be needed. ^[1][2]

Why is delayed treatment dangerous?
Because the condition can progress to sepsis, shock, and organ failure. ^[1][2]