Peritonitis - What is Peritonitis?

Peritonitis is an inflammation of the peritoneum, the serous membrane which lines part of the abdominal cavity and viscera. Peritonitis may be localized or generalized, and may result from infection (often due to rupture of a hollow organ as may occur in abdominal trauma or appendicitis) or from a non-infectious process.

Abdominal pain and tenderness

The main manifestations of peritonitis are acute abdominal pain, abdominal tenderness, and abdominal guarding, which are exacerbated by moving the peritoneum, e.g. coughing (forced cough may be used as a test), flexing one's hips, or eliciting the Blumberg sign (a.k.a. rebound tenderness, meaning that pressing a hand on the abdomen elicits less pain than releasing the hand abruptly, which will aggravate the pain, as the peritoneum snaps back into place).

The presence of these signs in a patient is sometimes referred to as peritonism. The localization of these manifestations depends on whether peritonitis is localized (e.g. appendicitis or diverticulitis before perforation), or generalized to the whole abdomen.

In either case pain typically starts as a generalized abdominal pain (with involvement of poorly localizing innervation of the visceral peritoneal layer), and may become localized later (with the involvement of the somatically innervated parietal peritoneal layer). Peritonitis is an example of an acute abdomen.

Collateral manifestations

• Diffuse abdominal rigidity ("washboard abdomen") is often present, especially in generalized peritonitis
• Fever
• Sinus tachycardia
• Development of ileus paralyticus (i.e. intestinal paralysis), which also causesnausea and vomiting

Complications

• Sequestration of fluid and electrolytes, as revealed by decreased central venous pressure, may cause electrolyte disturbances, as well as significant hypovolemia, possibly leading to shock and acute renal failure.
• A peritoneal abscess may form (e.g. above or below the liver, or in the lesser omentum
• Sepsis may develop, so blood cultures should be obtained.
• The fluid may push on the diaphragm, causing splinting and subsequent breathing difficulties.

If properly treated, typical cases of surgically correctable peritonitis (e.g. perforatedpeptic ulcer, appendicitis, and diverticulitis) have a mortality rate of about <10% in otherwise healthy patients, which rises to about 40% in the elderly, and/or in those with significant underlying illness, as well as in cases that present late (after 48h). If untreated, generalised peritonitis is almost always fatal.