Peritonitis is a life-threatening condition, which can be characterized as the penetration of bacteria into the abdominal cavity. The abdominal cavity (peritoneal cavity) is lined with a lining called the peritoneum. This membrane covers not only the cavity, but also the surfaces of all organs located within the abdominal cavity.
Peritonitis occurs when the abdominal cavity gets infected by bacteria. This may be due to a penetration from the outside, which is typical for open wounds of the abdomen, or when the bacteria come from abdominal organs. A common cause is rupture of the intestine or other parts of the digestive tract including stomach and duodenum by a peptic ulcer, appendix by appendicitis and large intestine by rupture of a diverticulum. Peritonitis can occur as a complication of inflammatory bowel diseases such as Crohn's disease and ulcerative colitis. In addition, the peritonitis is a severe complication of advanced cases of intestinal obstruction.
The peritoneum has a large surface area with many blood vessels. It is an ideal place for bacterial proliferation and absorption of their toxins into the bloodstream. The bacteria themselves can easily get into the blood and cause sepsis.
We distinguish bordered form of peritonitis, when the inflammation is restricted only to a part of the peritoneum, and diffuse peritonitis, which is associated with extensive inflammation in the abdominal cavity. The bordered form is less dangerous and it is a result of defensive measures of the abdominal cavity trying to prevent the infection from further spread. Diffuse peritonitis poses a direct threat to life.
Note: There are also less common cases of non-infectious peritonitis that are caused by local inflammation without bacterial presence. Such case can happen in a laparoscopic cholecystectomy when the gallbladder gets accidentally perforated and the bile flows out of the bladder into the abdominal cavity.
Peritonitis manifests with high fever and abdominal pain. The abdomen is painful when tapped or deeply palpated. Abdominal wall reacts with contractions of local muscles making the abdomen very stiff when touched. The patient may suffer from signs of sepsis, which can easily turn into a classic shock condition including drop of the blood pressure, palpitations, rapid breathing, pallor, general malaise, unconsciousness and death due to the failure of cardiovascular system. Extensive peritonitis is usually accompanied with paralytic ileus manifesting with constipation and vomiting.
Careful physical examination focused on the abdomen is necessary, preferably by a surgeon. The blood tests show signs of inflammation such as increased sedimentation rate, elevated CRP and high numbers of leukocytes. Simple abdominal X-ray is great as it can show signs of intestinal obstruction (characteristic air and fluid levels in the intestines), or air under the diaphragm in case of a rupture of the digestive tract. Other imaging methods may be used as well, such as the computed tomography of the abdomen. The final and definitive both diagnostic and curative method is a surgical intervention with opening the abdominal cavity.
Peritonitis must be handled as a very serous condition, the patient must be hospitalized with assured monitoration of all basic vital functions. The patient must have oxygen supply and intravenous acces for administration of infusions and large doses of antibiotics. The peritonitis often requires acute surgical intevention aimed to locate and remove any source of infection and to place a drain to take away any residual pus. Untreated extensive peritonitis is usually fatal and even full-scale intensive therapy may not be suficient to save the patient's life.