Peritonitis

Peritonitis is inflammation and infection of the peritoneum, the membrane lining the abdominal cavity. It is commonly categorized as primary, secondary, or tertiary. Primary peritonitis, also known as spontaneous bacterial peritonitis, occurs without an evident intra-abdominal source and is most often seen in patients with cirrhosis and ascites. Secondary peritonitis arises from a perforated viscus or another intra-abdominal infection, such as appendicitis, diverticulitis, or pancreatitis. Tertiary peritonitis refers to persistent or recurrent infection after initial treatment, frequently involving resistant organisms or immunocompromised hosts.

Causes and risk factors vary by category. Primary peritonitis is linked to ascites and cirrhosis; secondary peritonitis results from intra-abdominal contamination due to perforation, trauma, or postoperative complications. Risk factors include prior abdominal surgery, inflammatory diseases, peritoneal dialysis, and systemic immunosuppression.

Clinical features typically include acute or rapidly progressing abdominal pain with tenderness and guarding, abdominal distension, fever, tachycardia, and signs of sepsis in severe cases. Nausea, vomiting, and ileus may be present. Diagnosis relies on clinical suspicion supported by laboratory tests (elevated white blood cell count, inflammatory markers) and imaging (ultrasound or CT) to identify the source. In patients with ascites, diagnostic paracentesis with ascitic fluid analysis is important: a neutrophil count greater than 250 cells/µL and/or positive cultures support the diagnosis of peritonitis. Blood cultures may also be obtained.

Management requires immediate broad-spectrum intravenous antibiotics with later narrowing based on cultures, along with source control for secondary or tertiary peritonitis (surgical intervention or drainage). Supportive care includes fluid resuscitation, hemodynamic monitoring, and management of organ dysfunction. In spontaneous bacterial peritonitis, albumin may reduce renal failure risk. Prognosis depends on the underlying cause, the patient’s condition, and the timeliness of treatment; mortality remains significant in severe cases. Prevention focuses on risk reduction in cirrhotics and meticulous care in peritoneal dialysis to minimize infection.