Peritonitis is the inflammation of the peritoneal lining of the abdominal cavity (the peritoneum).
The peritoneum is a thin double‐layered serosal membrane that lines the wall and organs of the abdominal cavity. In between the parietal and visceral peritoneum, there is a potential space that contains a small amount of serous fluid. This space, the peritoneal cavity, is normally sterile.
A small quantity of peritoneal fluid is produced by mesothelial cells filling the potential space and allowing a frictionless sliding of the layers over each other. Peritoneal fluid is also produced as a transudate that coats the serosal surface of viscera.
The fluid is constantly being produced and resorbed through the large surface area of the peritoneum; therefore, for this reason, drugs are sometimes administered by intraperitoneal injection. Bacterial toxins are also absorbed readily and can cause inflammation of the peritoneum known as peritonitis.
Appreciate that peritonitis could be due to tuberculosis and could also be aseptic.
The aseptic type is usually due to chemical irritants like pancreatic juices, etc. Peritonitis usually ends up producing adhesions that may cause future bowel obstructions of varying degrees.
Classification of Peritonitis
Peritonitis can be classified into two;
- Localized peritonitis
- Generalized peritonitis
Most often, peritonitis is caused by an infection that spreads to the peritoneum from another part of the body. This is known as secondary peritonitis. The common causes of secondary peritonitis include perforations from stomach ulcer, a burst appendix, Crohn’s disease and diverticulitis.
These causes can be divided into localized and generalized causes.
A) Localized causes include:
B) Generalized Causes:
Bacterial infection of the peritoneal cavity.
Cirrhosis and ascites or
Renal failure patients having continuous ambulatory peritoneal dialysis.
Polymicrobial or nonbacterial due to spillage of bile, blood, gastric contents.
Pathophysiology of peritonitis
Inflammation of the peritoneum can result from contamination of the otherwise sterile peritoneal cavity by either an infection or a chemical irritant.
The aseptic type of peritonitis known as chemical peritonitis is usually due to chemical irritants like pancreatic juices. Perforation of a peptic ulcer or rupture of the gall bladder releases gastric juices or bile into the peritoneal cavity, causing an acute inflammatory response.
Bacterial peritonitis, on the other hand, is caused by a bacterial infection. The most common bacteria associated are; Klebsiella, Escherichia coli, Proteus or Pseudomonas bacteria. This is because these bacteria normally inhabit the bowel.
After these processes, the inflammatory and immune defence mechanisms of the body are activated to try and effectively eliminate the bacteria. However, these defence mechanisms may only eliminate small numbers of bacteria and then become overwhelmed by massive or continued contamination.
At this stage, the mast cells release a substance known as histamine and other vasoactive substances which lead to local vasodilation and increased capillary permeability. A type of white blood cells known as Polymorphonuclear leukocytes rush and infiltrate the peritoneum to so as to phagocytize pathogens.
The immune system tries to limit and localize the spread of infection in the peritoneum by releasing a substance known as Fibrinogen‐rich plasma exudate. This exudate promotes bacterial destruction and forms fibrin clots to seal off and segregate the bacteria to make it easier for the host defences to eradicate it.
Continued contamination of the peritoneum eventually leads to generalized peritonitis.
The inflammatory process leads to a shift of fluid into the peritoneal space known as third spacing depleting the blood volume causing hypovolaemia.
If the bacteria or the toxins produced by the bacteria get an entry into the bloodstream they lead to the development of septicaemia.
Spontaneous peritonitis is usually a complication of liver disease, such as cirrhosis. Advanced cirrhosis is usually followed by the development of ascites. The ascitic fluid is usually susceptible to bacterial infection.
Signs and symptoms
An individual with peritonitis will present with a number of complaints depending on the severity and extent of the infection, as well as the age and general health of the patient.
The patient often presents with evidence of;
An acute tender abdomen with guarding or rigidity of abdominal muscles
Abrupt onset of diffuse, continuous, sharp, localized abdominal pain and exacerbated by movement and coughing. The pain may localize and intensify near the area of infection. .
Systemic signs of peritonitis include fever, malaise, tachycardia and tachypnoea, and restlessness. The client may be oliguric and dehydrated.
Physical examination findings will reveal;
Tenderness with involuntary guarding:
Reflex contraction of overlying abdominal wall muscles;
Rebound tenderness may be present over the area of inflammation
The sudden removal of a palpating hand causes pain
The abdomen will be rigid,
Bowel sounds are markedly reduced or more typically absent due to paralytic ileus
Peritoneal inflammation inhibits peristalsis, resulting in paralytic ileus.
A progressive abdominal distention is noted.
Complications of peritonitis include the following:
- Multiple organs damage,
- Site infection following wound dehiscence.
- Enterocutaneous infection.
- Full haemogram,
- Urea and electrolyte levels
- Abdominal radiograph (erect AP and dorsal decubitus) may show air-fluid levels or air under the diaphragm in case of perforated viscera.
- Liver function tests,amylase,CRP,clotting profile
- Peritoneal fluid analysis
- Ct scan of the abdomen or laparoscopy
- Ascitic tap and cell count in case of ascites.
- Arterial Blood Gas analysis looking for metabolic acidosis, lactate levels or respiratory failure
Treatment will depend on the underlying cause (e.g. appendicectomy in appendicitis),
Correct fluid and electrolyte imbalance. These are usually disturbed by the movement of fluid and electrolytes into the third The disturbance could arise or be made worse by vomiting and/or diarrhoea.
Consider nasogastric suction, which is usually necessary because of organ hypotonia.
Use antibiotics to cover a broad spectrum of Combinations advised in order to get the appropriate cover are cefuroxime 750mg 8 hourly + metronidazole 500mg IV 8 hourly for 7 days.
Alleviate pain only once a diagnosis has been made.
Inflammatory response modulation therapy
Exploratory laparotomy is a must in secondary peritonitis in order to repair or remove the diseased organ. Laparotomy also facilitates peritoneal lavage of the necrotic debris and pus.
The cause of peritonitis may also need to be surgically treated. For instance, if a burst appendix caused the peritonitis, the appendix will need to be removed.
Some people develop abscesses in their peritoneum that need to be drained using an ultrasound scanner to guide the needle to the abscess.
Direct attention at the primary cause of peritinotis
Send pus for culture and sensitivity