Peritonitis

What is Peritonitis?

Peritonitis is inflammation of the peritoneal lining resulting from microbial invasion or chemical irritation. This condition often presents with severe abdominal pain, but findings may be subtle in patients with ascites or immunocompromise. Acute peritonitis may begin with localized abdominal pain that later becomes diffuse, often with fever and tachycardia. Without prompt treatment, the inflammation can lead to sepsis within hours or days. Individuals with cirrhosis, those on peritoneal dialysis, or patients with visceral perforation face the highest risk.

What causes Peritonitis?

Peritonitis occurs when bacteria or irritating fluids enter the normally sterile peritoneal cavity. Visceral perforation from trauma, diverticulitis, or peptic ulcer disease introduces enteric flora into the space. In cirrhotic patients, impaired local immunity allows gut microbes to translocate into ascitic fluid. Catheter contamination often introduces pathogens for those undergoing peritoneal dialysis. Sterile irritants, such as pancreatic enzymes, bile, gastric acid, or blood, can also cause chemical peritonitis.

What are the signs and symptoms associated with Peritonitis?

Clinical presentation typically begins with localized pain that becomes diffuse across the abdomen. Patients present with rigid guarding, rebound tenderness, and diminished bowel sounds. Systemic inflammation or sepsis may cause fever, tachypnea, tachycardia, hypotension, or shock. Local bowel irritation results in nausea, vomiting, and ileus, a temporary lack of muscle contractions in the intestine.

In individuals with cirrhotic ascites, peritonitis signs and symptoms may appear subtle. Clinicians should monitor for encephalopathy (altered mental status), worsening renal function, or mild abdominal discomfort. These clues prompt a timely paracentesis, the removal of fluid from the abdomen, to identify underlying infection.

How is Peritonitis diagnosed?

Laboratory studies may show leukocytosis with a left shift, electrolyte abnormalities, metabolic acidosis, or elevated lactate, but diagnosis is guided by the overall clinical picture. Upright abdominal radiographs or CT scans detect free air or abscesses to guide surgical consultation. For ascitic patients, diagnostic paracentesis confirms infection when the polymorphonuclear (PMN) cell count reaches 250 cells/mm³ or higher. Ascitic fluid culture can identify the organism and guide antimicrobial therapy.

How is Peritonitis treated?

Management prioritizes hemodynamic stabilization, source control, and immediate antimicrobial therapy. Clinicians resuscitate the individual with intravenous fluids while initiating broad-spectrum antibiotics covering anaerobes and enteric Gram-negative bacteria. Secondary peritonitis from perforation, ischemia, necrosis, or abscess requires urgent source control, which may involve surgery or image-guided drainage. Patients with spontaneous bacterial peritonitis may require albumin, especially when they are at increased risk for renal dysfunction. Long-term care often includes prophylactic antibiotics to reduce the risk of recurrence.

What are the most important facts to know about Peritonitis?

• Peritonitis is inflammation of the peritoneum, usually caused by infection or chemical irritation.
• Secondary peritonitis often results from visceral perforation and requires urgent source control.
• Peritonitis signs and symptoms include severe abdominal pain, guarding, rebound tenderness, abdominal rigidity, fever, and tachycardia.
• Diagnosis is based on clinical findings supported by laboratory tests, imaging, and analysis of peritoneal fluid when ascites is present.
• Treatment includes fluid resuscitation, broad-spectrum antibiotics, and source control when needed.