Medically Reviewed on 2/28/2023

What is peritonitis?

Abdominal Pain
The signs and symptoms of peritonitis may vary depending on the cause of the inflammation.

The definition of peritonitis is as follows: inflammation of the peritoneum (the thin layer of tissue covering the inside of the abdomen and various organs within the abdomen). Peritonitis usually develops from a bacterial or less frequently, fungal infection; but there are other less often encountered causes of peritoneal inflammation.

Most individuals need quick or emergent treatment of peritonitis due to infection because infecting organisms can spread rapidly in individuals and become life-threatening.

What is the most common type of peritonitis?

The most common type of peritonitis is secondary peritonitis, usually caused by leakage or perforation of an abdominal organ, like the appendix. However, another common type of peritonitis is spontaneous bacterial peritonitis (SBP) which is most often associated with individuals that have abdominal ascites fluid.

How does someone get peritonitis?

The causes of peritonitis can be grouped into five categories. The following is a list of these five categories and some examples of their causes:

  1. Primary peritonitis: Spontaneous bacterial peritonitis (SBP) is associated with ascites from patients with cirrhosis (highest risk patients for SBP), heart failure, or patients with systemic lupus and nephrosis. The majority of the cases are caused by a microbial infection.
  2. Secondary peritonitis: Secondary peritonitis is caused by infection due to a perforated appendix, perforated ulcers, diverticulitis, or bowel strangulation.
  3. Tertiary peritonitis: Tertiary peritonitis is caused by the bacterium Mycobacterium tuberculosis (TB), and is referred to as tuberculosis peritonitis.
  4. Chemical peritonitis (also termed sterile peritonitis): Chemical peritonitis is caused by leakage of sterile fluids that are irritants to the peritoneum; for example, bile, blood, or barium used as a contrast agent during procedures and tests.
  5. Peritoneal abscess: Peritoneal abscess is caused by an infected fluid collection that is encapsulated and/or adjacent to visceral organs and/or the peritoneum.

Some healthcare professionals choose not to categorize peritonitis; they simply use a modifier placed in front of or behind the term "peritonitis" to describe the patient's disease. Below are definitions of a sampling of some of these terms:

  1. Bacterial peritonitis: any type of peritonitis including spontaneous bacterial peritonitis caused by a bacterial species.
  2. Peritonitis appendicitis: Peritonitis is caused by leakage of the intestinal contents from the appendix.
  3. Acute peritonitis: initial rapid onset of peritonitis symptoms.
  4. Meconium peritonitis: fetal stool that escapes from the fetal bowel before birth by rupture and results in sterile peritonitis.
  5. Bile peritonitis: leakage of bile fluid into the peritoneum.
  6. Septic peritonitis: infection of the peritoneum that has spread to the blood.
  7. Sclerosing peritonitis: inflammation of the visceral and parental surfaces of the abdominal cavity characterized by fibrous thickening of the peritoneum.
  8. Pelvic peritonitis: inflammation involving the peritoneum surrounding the uterus and Fallopian tubes.
  9. Tuberculosis peritonitis: inflammation of the peritoneum by Mycobacterium bacteria.
  10. Ascites peritonitis: infection of ascites fluid causing inflammation of the peritoneum.
  11. Peritonitis sintomas: Spanish for peritonitis symptoms.


Peritonitis See pictures of Bacterial Skin Conditions See Images

What are the symptoms of peritonitis?

Abdominal Pain
Abdominal tenderness or pain that increases when the abdomen is touched or moved (palpation). Source: iStock

The signs and symptoms of peritonitis may vary depending on the cause of the inflammation; however, there are relatively common indicators that suggest a person may have peritonitis.

People usually have abdominal discomfort and one or more of the following:

What types of doctors diagnose and treat peritonitis?

Peritonitis can rapidly develop into a life-threatening problem. Depending on its cause many different doctors will be involved in the treatment; consequently, peritonitis is seen and treated by emergency medicine doctors, critical-care specialists, dialysis specialists, infectious disease specialists, gastroenterologists, hospitalists, internal medicine specialists, and surgeons. Other specialists may need to treat underlying causes.

Can a blood test detect peritonitis?

Because peritonitis can be life-threatening, early diagnosis is important. Healthcare professionals will take a history and perform a physical exam on the patient. They also may ask for details about dialysis, ascites, and trauma to the abdomen. The patient may have some mild discomfort while the doctor examines his/her abdomen.

Tests that may be ordered include a complete cell count (CBC), blood cultures, and imaging tests such as an ultrasound or CT scan of the abdomen/pelvis.

Some patients who do peritoneal dialysis will be asked for a sample of the dialysis fluid so that it can be examined. In some patients with abscesses, an examination of the abscess fluid is done.

What are the three stages of peritonitis?

Generally, peritonitis is classified into three stages based on the progression and severity of the condition. These three stages include the following:

  1. Acute peritonitis
    • The initial stage of peritonitis is characterized by a sudden onset of symptoms.
    • Symptoms of acute peritonitis include:
    • Treatment for acute peritonitis includes the administration of antibiotics and hospitalization.
  2. Peritoneal abscess
    • Acute peritonitis can develop into a peritoneal abscess if left untreated. This stage is characterized by pus accumulation in the abdominal cavity, creating an abscess.
    • Symptoms of a peritoneal abscess include:
    • Treatment of a peritoneal abscess includes drainage of the abscess and antibiotics.
  3. Diffuse peritonitis
    • Peritonitis progresses to the third stage, known as diffuse peritonitis if the infection continues to spread. This stage is characterized by widespread inflammation, as well as damage to the peritoneum and surrounding organs.
    • Symptoms of diffuse peritonitis include:
      • Severe abdominal pain
      • Fever
      • Vomiting
      • Signs of sepsis
    • Treatment of diffuse peritonitis includes surgery to remove damaged tissue, as well as antibiotics and supportive care.

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Is peritonitis difficult to treat?

The treatment for peritonitis begins with correction of the underlying process (for example, appendicitis that has caused peritonitis or bile leakage into the abdominal cavity). In most people with peritonitis, there is an infectious source so intravenous antibiotic therapy is started immediately.

The patient also is likely to require supportive care such as avoiding dehydration, avoiding pulmonary infections that are secondary to peritonitis, and possibly renal system support (especially in patients undergoing dialysis).

Reducing the inflammatory response also may be part of supportive treatment.

Some individuals may require percutaneous abscess drainage to augment antimicrobial therapy. Although there are specific suggestions for antimicrobial therapy for treating infectious peritonitis, optimal antimicrobial therapy should be individualized and depends on the types of infecting organisms and their sensitivity to antimicrobials.

Can peritonitis be fatal?

The prognosis for individuals who develop peritonitis depends on both the underlying cause and how rapidly the disease is treated. The prognosis can range from good to poor. For example, individuals who are treated appropriately with antimicrobials and surgery for peritonitis caused by appendicitis often have a good outcome. However, individuals with long-standing diseases such as liver failure that develop hepatorenal syndrome and peritonitis have a poor prognosis.

What are the complications of peritonitis?

The complications of peritonitis can be extremely serious, and include:

Can peritonitis be prevented?

Prevention or reduction in the chance of developing peritonitis can be done by preventing underlying causes (for example, trauma, ulcers, alcoholic cirrhosis, and pelvic inflammatory disease).

Individuals who are obtaining peritoneal dialysis should be very careful about hand and fingernail cleanliness to avoid contamination of the dialysis catheter. Skin adjacent to the dialysis catheter should be cleaned daily, and patients should follow instructions given to them by their dialysis team.

Preventive use of antimicrobials has been used to reduce the risk of peritonitis; however, if this technique is used, it may generate antibiotic-resistant organisms over time.

Individuals should discuss how to decrease or prevent the likelihood of peritonitis recurrence with their healthcare professionals.

Medically Reviewed on 2/28/2023
Medically reviewed by Joseph Palermo, DO; Board Certificate: Internal Medicine/Geriatric Medicine

Daley, B. "Peritonitis and Abdominal Sepsis." Medscape. Updated Feb 23, 2015.