An acute abdomen is characterized by inflammation or irritation of the peritoneum, which is the tissue that lines the wall of the abdomen and covers the abdominal organs. Sometimes an intra-abdominal abscess can cause this condition to occur. Alternatively, in secondary peritonitis, the inflammation can be traced to another cause – most commonly the spread of an infection from the digestive system or bowels. Here, bacteria enters the peritoneum via a hole in the gastrointestinal tract that is created by a ruptured appendix, stomach ulcer or perforated colon. Alternatively, the infection may occur when pancreatic enzymes leak into the peritoneum due to pancreatitis, or when bile leaks from the biliary tract due to an injury. An infected peritoneal dialysis catheter may also be to blame for the condition. Someone with an acute abdomen will usually complain of serious abdominal pain and present with a distended abdomen, fever, low urine output and significant thirst. Treating peritonitis may involve surgery to remove a peritoneal dialysis catheter, antibiotic medications, and IV therapy to address dehydration. Most patients with this disorder need to be hospitalized and evaluated for possible appendicitis or diverticulitis.