The tremendous complexity of the abdomen makes diagnosis and treatment of intraperitoneal disease one of the greatest challenges in clinical medicine. Many intra-abdominal processes prompt urgent evaluation and some of these require immediate intervention. These conditions manifest via peritonitis, which is inflammation or infection of the lining of the abdominal cavity. Peritonitis is classified as primary, secondary, or tertiary on the basis of its underlying pathophysiology; the distinction is useful when considering relevant microbiology and treatment.
Primary peritonitis occurs when bacteria seed the peritoneum hematogenously, via indwelling catheters, or by translocation across intestinal walls. Spontaneous bacterial peritonitis (SBP) and tuberculous peritonitis are examples of this process.
Secondary peritonitis is caused by inflammation and/or infection arising in abdominal organs as occurs with hollow viscus perforation, biliary tract disease, bowel ischemia, pancreatitis, and pelvic inflammatory disease. The process is generally polymicrobial, but the specific pathogens vary based on the source of infection.
Tertiary peritonitis refers to recurrent or persistent intra-abdominal infection after apparent definitive intervention with antibiotics and drainage.
The single most common chief complaint for United States emergency department visits is abdominal pain. Although many such patients are suffering from self-limited disease, some require definitive intervention and an error or delay in diagnosis can be disastrous.
The most common cause of primary peritonitis is catheter-related peritonitis, due to peritoneal dialysis (Tenckhoff) catheters or peritoneovenous shunts.