Causes and Triggers
Peritonitis is primarily caused by an infection that breaches the sterile environment of the abdominal cavity. Secondary peritonitis occurs when bacteria or enzymes enter the peritoneum through a hole or tear in the gastrointestinal tract, often due to a ruptured appendix, perforated stomach ulcer, or severe diverticulitis. Spontaneous bacterial peritonitis (SBP) is a different form that develops in people with liver disease, specifically cirrhosis, where fluid builds up in the abdomen and becomes infected without an obvious rupture. Another common cause is infection related to peritoneal dialysis, where germs enter through the catheter used to filter blood.

Risk Factors
Several factors increase the likelihood of developing this condition. Individuals with cirrhosis and ascites (fluid buildup) are at the highest risk for the spontaneous type. Patients undergoing peritoneal dialysis face a constant risk of infection if catheter hygiene is compromised. Other risk factors include:

• A history of pelvic inflammatory disease or abdominal surgery.
• Conditions that weaken the immune system, making infections harder to fight.
• Trauma to the abdomen, such as a knife or gunshot wound.
• Chronic digestive diseases like Crohn's disease or diverticulitis.

Prevention
Preventing peritonitis largely involves managing underlying health conditions and maintaining strict hygiene. For dialysis patients, washing hands thoroughly and following sterile techniques during catheter exchanges are the most effective preventive steps. People with liver disease may be prescribed preventative antibiotics if they are at high risk for spontaneous infection. While it is difficult to prevent emergencies like appendicitis, seeking immediate medical care for severe abdominal pain can prevent the appendix from bursting and spreading infection.

Signs and Symptoms
The hallmark symptom of peritonitis is sudden, severe abdominal pain that worsens with movement, coughing, or touch. The abdomen often becomes swollen and feels rigid or "board-like" due to the muscles tensing up. As the infection progresses, systemic symptoms typically appear. Clinically meaningful signs include:

• High fever and chills.
• Nausea and vomiting.
• Loss of appetite and inability to pass gas or stool.
• Low urine output.
• Extreme thirst and fatigue.

Diagnosis
Clinicians diagnose peritonitis through a combination of physical exams and diagnostic testing. During the exam, the doctor will check for tenderness and abdominal guarding. Blood tests are performed to look for an elevated white blood cell count, which signals infection. Imaging tests such as X-rays, CT scans, or ultrasounds help visualize fluid buildup, free air indicating a rupture, or abscesses. If there is fluid in the abdomen, doctors may perform a paracentesis, using a needle to withdraw a fluid sample for laboratory analysis to identify the specific bacteria and guide antibiotic treatment.

Differential Diagnosis
The condition can be confused with other abdominal emergencies. Doctors must rule out appendicitis, pancreatitis, ectopic pregnancy, or active diverticulitis before confirming peritonitis, although these conditions can sometimes cause peritonitis if they lead to a rupture.

Medical and Surgical Treatment
Treatment for peritonitis is aggressive and typically requires hospitalization. The primary approach involves intravenous (IV) antibiotics or antifungal medications to fight the infection. If the peritonitis is secondary to a ruptured organ, surgery is almost always necessary to repair the hole, remove infected tissue (such as an inflamed appendix), and rinse the abdominal cavity. For spontaneous bacterial peritonitis associated with liver disease, treatment focuses on antibiotics without surgery. Patients on peritoneal dialysis may receive antibiotics directly into the peritoneum through their catheter.

Supportive Management
Alongside fighting the infection, supportive care is crucial to stabilize the patient. This involves administering intravenous fluids to correct dehydration and maintain blood pressure. Pain management is provided to relieve severe discomfort. In some cases, a nasogastric tube may be inserted through the nose into the stomach to remove gas and fluid, relieving pressure on the bowel.

When to Seek Medical Care
Peritonitis is a medical emergency. You should seek immediate emergency care if you experience severe, unexplained abdominal pain, especially if it is accompanied by fever, vomiting, or a swollen belly. Patients on peritoneal dialysis should contact their healthcare provider immediately if their dialysis fluid becomes cloudy or if they notice redness around the catheter site. Prompt action is vital because the infection can spread rapidly and become life-threatening.

Severity and Complications
Peritonitis is a severe condition that can be fatal if not treated promptly. The infection can spread into the bloodstream, leading to sepsis and septic shock, which causes dangerously low blood pressure and organ failure. Other complications include the formation of intraperitoneal abscesses (pockets of pus) and adhesions (bands of scar tissue) that can cause bowel obstructions months or years later. The condition is particularly dangerous for older adults and those with compromised immune systems.

Prognosis
The long-term outlook depends on the cause of the infection and how quickly treatment is initiated. With early diagnosis and modern antibiotic or surgical treatment, the prognosis is generally good, and most people recover fully. However, spontaneous bacterial peritonitis in patients with liver cirrhosis has a high recurrence rate and is associated with a poorer prognosis due to the underlying liver failure. Survival rates are significantly higher when the condition is treated before the onset of shock or organ dysfunction.

Impact on Daily Life and Recovery
Recovery from peritonitis often requires a hospital stay ranging from a few days to several weeks. Upon returning home, patients typically experience fatigue and weakness, requiring time off from work or school. Daily activities may be limited, especially after surgery; lifting heavy objects or strenuous exercise is usually restricted for several weeks to allow the abdominal wall to heal. Emotional support may be needed as patients recover from the trauma of a medical emergency. For those on dialysis, the treatment regimen may need to be adjusted, or the catheter replaced, temporarily disrupting their routine.

Questions to Ask Your Healthcare Provider

• What was the specific cause of my infection, and is it likely to happen again?
• Are there any specific signs of complications I should watch for at home?
• When can I resume normal activities like driving, working, or exercising?
• Do I need to make any changes to my diet while my bowel heals?
• If I am on dialysis, do I need to change my catheter care routine?

Q: Is peritonitis contagious?
A: No, peritonitis itself is not contagious and cannot be spread from person to person, although the bacteria causing the infection can be transmissible in other contexts.

Q: Can peritonitis heal on its own without treatment?
A: No, peritonitis is a life-threatening infection that does not resolve on its own; it requires immediate medical intervention with antibiotics and often surgery.

Q: How does peritoneal dialysis cause peritonitis?
A: It can occur if germs enter the abdomen through the catheter or if the sterile equipment is contaminated during the dialysis exchange process.

Q: What is the difference between primary and secondary peritonitis?
A: Primary peritonitis (spontaneous) occurs due to infection of fluid in the abdomen (common in liver disease), while secondary peritonitis is caused by a rupture or hole in an abdominal organ.

Q: Is peritonitis always fatal?
A: It is not always fatal, especially with modern medicine, but it has a high mortality rate if left untreated or if treatment is delayed until sepsis sets in.