Acute abdomen
Peritonitis is an inflammation (irritation) of the peritoneum, the tissue that lines the wall of the abdomen and covers the abdominal organs.
A collection of pus in the abdomen, called an intra-abdominal abscess, may cause peritonitis.
See the specific types of peritonitis:
Turnage RH, Richardson KA, Li BD, McDonald JC. Abdominal Wall, Umbilicus, Peritoneum, Mesenteries, Omentum, and Retroperitoneum. In: Townsend CM, Beauchamp RD, Evers BM, Mattox KL, eds. Sabiston Textbook of Surgery. 18th ed. St. Louis, Mo: WB Saunders; 2008:chap 43.