Peritonitis is an inflammation, usually an infection, of the peritoneum and the peritoneal cavity.
The peritoneum is a serous membrane that surrounds the abdominal viscera and the abdominal cavity. It has two layers, forming the space between them the peritoneal cavity. When this structure is colonized by microorganisms it gives a serious picture that requires a rapid intervention.
Anatomy of the peritoneum
The peritoneum is a membrane that lines the abdominal cavity and forms folds to cover the abdominal viscera . The viscera covered entirely by peritoneum are called intraperitoneal, while those that are only partially covered are retroperitoneal.
The limits of the peritoneum are:
- Upper limit: diaphragm
- Lower limit: pelvic floor
- Lateral limits: limits of the abdominal cavity
This membrane has two layers, the parietal peritoneum, which covers the abdominal cavity; and the visceral, which covers the viscera. Between the two layers a cavity is defined, which is the peritoneal cavity.
This cavity is closed in men and opened through the fallopian tubes in women. It contains between 50 and 100 ml of a serous fluid called ascitic fluid.
The folds of the peritoneum are formed by mesos, ligaments and omiplons, which divide the abdominal cavity into nine spaces and direct the exit of the different fluids from the cavity, so that it is possible to predict where the possible infections will spread.
Types of peritonitis
Peritonitis can be divided based on different criteria:
- According to its location: generalized or localized
- According to evolution: acute or chronic
- According to the pathogenesis: primary, secondary or tertiary
- According to the etiology: septic (produced by bacteria) or aseptic (irritation of the peritoneum without the presence of bacteria)
Next we will see the types of peritonitis according to their pathogenesis.
It is an infection of the ascitic fluid with inflammation of the peritoneum in which there is no abdominal focus of infection. It is not very frequent, it occurs more during the pediatric age. Within this pathology different pictures can be differentiated:
Primary peritonitis in cirrhotic patients
It is a picture that appears in up to 25% of patients with cirrhosis and their mortality is high. Liver cirrhosis alters the defenses of the individual, so it favors bacterial proliferation. The bacteria come from the intestinal lumen or from extraintestinal infections, such as pneumonia or a urinary tract infection.
The most common is that they are due to a single bacterial type, unlike secondary peritonitis where there is usually more than one type of microorganism. The most frequent are Escherichia coli and bacteria of the genus Streptococcus.
It is diagnosed with an aspirate of ascitic fluid for analysis. This fluid will have few proteins and an increase in neutrophils (more than 250 per cubic mm), blood cells that participate in the defense against infections. With a culture of the liquid you can know the microorganism that produces them. It is a condition that requires rapid antibiotic treatment.
Primary peritonitis by peritoneal dialysis
Peritoneal dialysis is a therapeutic procedure to clean the peritoneal cavity. It consists in introducing sterile liquid into the peritoneal cavity with a catheter. After a few hours this liquid is removed, dragging the waste products that were in this cavity.
In some cases the cavity can be contaminated and a picture of peritonitis appears. It is diagnosed because the patient will be feverish and have abdominal pain shortly after performing the procedure.
In addition, the ascitic fluid acquires a cloudy color with an increase in leukocytes, blood cells that are part of the immune system. A crop may also be useful in this case. To treat this condition, antibiotics should be introduced with the dialysate, checking the catheter and, if necessary, removing it.
In this case the inflammation of the peritoneum is a consequence of an intestinal infection. It may be due to a mild infection, in which the intestinal wall is not perforated; or severe symptoms with intestinal perforation.
The most common is peritonitis as a complication of appendicitis , in which the wall of the appendix ruptures and the bacteria reach the peritoneum.
Although intestinal perforation due to infection is the most common cause of secondary peritonitis, there are other causes. Inflammation of the peritoneum may be due to an infiltration of tumor cells by the spread of a cancer. It can also be a consequence of a postoperative or trauma.
The intestinal wall contains different microorganisms that form the intestinal flora . This flora varies in each intestinal tract, so that depending on the place where the perforation occurs, the bacteria will be one or the other. For this reason these infections are usually polymicrobial.
Patients with peritonitis have fever and localized abdominal pain. In addition, leukocytes increase in the analytical. In severe cases, the pain is widespread and the patient shows signs of multiorgan involvement. An abdominal x-ray may reveal the presence of abdominal gas.
Once the peritonitis is suspected, the test that provides more information is the CAT scan. Although in mild cases it may not be necessary, with an abdominal CT it is possible to identify the infection focus, the cause, the presence of abscesses or free fluid, and so on.
The treatment must be urgent, both surgical to correct the perforation or the cause of the inflammation; as a doctor with antibiotics and fluid therapy to stabilize the patient.
It is a less frequent picture, associated with patients with comorbidities or immunosuppressed . The treatment for primary or secondary peritonitis has failed and the infection is persistent even if the infectious focus is controlled.
This peritonitis is usually generalized, sometimes associated with multi-organ involvement. In this case it is necessary to extract the fluid from the abdomen and put a specific treatment against the causative microorganism.