What is peritonitis?
Peritonitis is infection (or inflammation) of the peritoneum, which is a two-layered membrane covering both the surfaces of the organs that lie in the abdominal cavity and the inner surface of the abdominal cavity itself. It is frequently life-threatening and acute peritonitis is a medical emergency. Outlook for untreated peritonitis is very poor.
The abdominal organs, such as the stomach and liver, are wrapped in a thin, tough membrane called the visceral peritoneum. The abdominal walls are similarly lined (parietal peritoneum). A protective layer of fat contained in a membrane (the omentum) sits between the organs and the abdominal wall. Lubricating fluid allows all these membranes to slide smoothly over each other. The main function of the peritoneum is to permit free movement of the internal organs during digestion. Peritonitis is inflammation of the peritoneum caused by bacterial infection. This is a life threatening emergency that needs prompt medical treatment.
A major cause of bacterial peritonitis is internal perforation of the gastrointestinal tract, contaminating the abdominal cavity with bacteria from gastric contents. This may result as a complication of an intestinal foreign body or a ruptured appendix, a possible consequence of untreated acute appendicitis. The possibility of peritonitis is the reason why acute appendicitis warrants fast treatment (generally, appendicectomy).
Peritonitis may be primary (meaning that it occurs spontaneously, and not as the result of some other medical problem) or secondary (meaning that it results from some other condition). It is most often due to infection by bacteria, but may also be due to some kind of a chemical irritant (such as spillage of acid from the stomach, bile from the gall bladder and biliary tract, or enzymes from the pancreas during the illness called pancreatitis). Peritonitis has even been seen in patients who develop a reaction to the cornstarch which is used to powder gloves worn during surgery. Peritonitis with no evidence of bacteria, chemical irritant, or foreign body has occurred in such diseases as systemic lupus erythematosus, porphyria, and familial Mediterranean fever. When the peritoneum gets contaminated by blood, the blood can both irritate the peritoneum and serve as a source of bacteria to cause an infection. Blood may leak into the abdomen due to a burst tubal pregnancy, an injury, or bleeding after surgery.