What is peritonitis?

The peritoneum is the thin tissue that lines the inside of your abdomen (belly) and covers the abdominal organs. Peritonitis is the term for inflammation of the peritoneum. Usually, an infection causes peritonitis. An injury or certain diseases also can cause it. It is important to evaluate the cause of peritonitis right away. Left untreated for too long, some forms of peritonitis can cause other serious health problems.

Symptoms and Causes

What causes peritonitis?

Infectious agents including, but not limited to, bacteria and fungi causes peritonitis. Sometimes the infection begins in the peritoneum. More often, the infection spreads from another area of the body.

Some of the most common reasons infection could spread to the peritoneum include:

  • Burst appendix.
  • Stomach ulcer.
  • Inflammation of the pancreas (pancreatitis).
  • Severe abdominal injury such as a knife wound.
  • Infection after abdominal surgery.
  • Digestive conditions such as diverticulitis or Crohn's disease.
  • Infection can also translocate from the gut in certain conditions such as liver failure.

What are the symptoms of peritonitis?

Different people experience different peritonitis symptoms. The most common symptoms are:

  • Severe pain in the abdomen that gets worse when you move.
  • Nausea and vomiting.
  • Fever.
  • Abdomen that is swollen or tender to the touch.
  • Passing smaller amounts of stool or change in stool habits.
  • Unexplained weight loss.

Diagnosis and Tests

How is peritonitis diagnosed?

To diagnose peritonitis, your doctor will do a physical exam to check if your abdomen is tender and if it feels firm or soft. Blood tests and other tests that provide images of the inside of your abdomen may also be used to determine the cause of the problem. These may include a CT scan or ultrasound.

Management and Treatment

How is peritonitis treated?

It is important to treat acute infectious peritonitis quickly, so the infection does not spread to other parts of your body and cause more serious health problems. Treatment for peritonitis typically starts with antibiotics to get rid of the infection. You might need to take these medicines for up to two weeks.

If the infection seriously damages the peritoneum, your doctor may need to perform surgery to remove the infection. Surgery may also be necessary to correct the initial cause of the infection, such as in appendicitis or perforated bowels.

Outlook / Prognosis

What is the outlook for people with peritonitis?

The outlook for people with peritonitis depends on the source and type of peritonitis. People with weak immune systems and the elderly are more at risk for complications than others. Early diagnosis is very important for anyone with peritonitis to receive effective treatment.

Last reviewed by a Cleveland Clinic medical professional on 05/29/2018.


  • National Health Service. Peritonitis. ( Accessed 5/30/2018.

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