31st July 2023

Peritonitis

Peritonitis refers to inflammation of the peritoneal cavity. It can either be localised or generalised, the latter of which is much more serious, as it can lead to life-threatening sepsis.

Causes of peritonitis include:

• Bowel perforation
• Any abdominal pathology that causes marked inflammation, i.e. appendicitis, diverticulitis, strangulating intestinal obstruction, acute pancreatitis.
• Irritation from intraperitoneal blood from any source, i.e. ruptured aortic aneurysm, ruptured ectopic pregnancy, ruptured spleen, trauma.
• Infectious peritonitis from peritoneal-systemic shunts, drains and dialysis catheters in the peritoneal cavity.
• Spontaneous bacterial peritonitis (SBP) occurs when there is no obvious infective trigger, but widespread inflammation (specifically of the ascitic fluid) occurs, and the causative organisms are generally bowel flora. Particularly associated as a complication of chronic liver disease.

Generalised peritonitis presents as severe generalised abdominal pain. Common signs include a firm abdomen, and lack of abdominal movement with respiration, guarding, rebound tenderness, severe pain to light palpation, and percussion tenderness (all of which are indicative of a ‘peritonitic’ abdomen). It is also associated with shock.

Management and treatment are of the acute abdomen, as above.

If an abdomen is peritonitic, then a bowel perforation should be suspected, and an erect chest x-ray should be performed to assess for pneumoperitoneum. A CT abdomen is the gold standard imaging investigation, as it will help to determine the cause. If fit for surgical intervention, then a bowel perforation needs urgent surgical repair.

Generalised peritonitis leads to severe dehydration and electrolyte disturbances, due to the fluid shifts between the peritoneal cavity and the bowel. Other complications include acute respiratory distress syndrome, renal failure, liver failure and disseminated intravascular coagulation. These complications are life-threatening; hence, any patient with a peritonitic abdomen requires urgent treatment.