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This is inflammation of the peritoneum. It can be generalised or localised, and is often associated with rupture of an internal organ, e.g. as occurs in trauma. In usually represents a surgical emergency.

There is almost always some localised peritonitis with inflammation of an underlying organ, e.g. with cholecystitis. The treatment in these cases is just treatment of the underlying condition.
Generalised peritonitis is far more serious, and is a result of direct irritation of the peritoneum.
In peritonitis, the peritoneum will produce inflammatory factors that will lead to intestinal dilatation and paralytic ileus.
On investigation, there will be an absence of bowel sounds.


  • More common in men than women.
  • In women they can occur from ruptures to the reproductive organs, such as an ectopic pregnancy, infected fallopian tube, or ovarian cyst.


  • Sudden onset acute abdominal pain that is exacerbated by any movement, e.g. coughing.
  • Often the pain may begin generalised but then become localised. This is because at first is may be the visceral nerve fibres that are activated (which are poorly localising) and then later the parietal nerve fibres are activated.
  • Shock and fever
  • Washboard rigidity
  • Fever
  • Pulse >100 (sinus tachycardia) – the rhythm will still be normal.
  • Severe abdominal pain
  • Nausea and vomiting
  • Abdominal swelling
  • Dullness may occur after 2-4 hours.


  1. Infected peritonitis
    1. Perforation of part of the GI tract, or, in women, of the reproductive system – this could be due to ingestion of a sharp object, e.g. a fishbone! Or could be due to trauma, or an ulcer etc. In these cases you will most often find Gram negative bacteria and anaerobic bacteria in the peritoneum. A common example is E. coli.
    2. Disruption of the peritoneum – e.g. by surgery or trauma. This can result in bacteria in the peritoneum from the external environment. In this case, the most common causing agent is Staphylococcus aureus.
    3. Spontaneous bacterial peritonitis (SBP) – this can occur in children and in those with ascites (i.e. in severe liver disease). It is treated differently to other types of peritonitis; usually only requiring antibiotic treatment.
    4. Systemic infections – e.g. such as TB can very rarely result in peritonitis.
  2. Non-Infected Peritonitis
    1. Leakage of sterile bodily fluids into the peritoneum – e.g. such as blood, bile urine etc. It is very important to note that although these fluids are sterile at first, they will usually become infected once in the peritoneal cavity, causing full blown peritonitis within 24-48 hours.
    2. Auto-immune disease – such as Lupus can cause peritonitis.


  • Loss of fluids / disturbance of electrolyte balance – hypovolaemia may result and this could bring about shock or even renal failure.
  • Difficulty breathing – due to pressure of fluid on diaphragm.
  • Peritoneal abscess
  • Any delay in treatment can produce a worse toxaemia and septicaemia.
  • Abscess – These are relatively common after surgery and should be suspected if the patient’s condition does not improve and there is continuing fever and high white cell count.


  • Erect CXR to check for air under the diaphragm
  • Serum amylase to rule out pancreatitis.
  • Ultrasound / CT to confirm diagnosis


  • IV fluids and electrolytes are given to try and reverse hypovolemia and restore the normal electrolyte balance.
  • IV antibiotics may be given if it is an infective peritonitis.
  • Surgery – a laparotomy is performed. This will only be performed after a reasonable urine output has been attained. This will try to repair the perforation, and the contents of the peritoneal cavity will be washed out. The surgery often has two purposes in that it will sort out the underlying problem as well as treat the peritonitis. Some surgeons like to use an antibiotic wash, however there is no evidence to suggest this is more effective that just using saline solution.
If left untreated, peritonitis is almost always fatal. Peritonitis that can be easily treated surgically (e.g. peritonitis due to perforations) has a mortality of <10%, rising to about 40% in the elderly.
The later a case presents, the more likely it is to have fatal consequences, particularly those that present after 48 hours.
After surgery, the patient will be fed IV whilst they have time to recover


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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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