What are peritoneal signs?

What Are Peritoneal Signs?

Peritoneal signs are physical examination findings that indicate inflammation of the peritoneum (peritonitis), characterized primarily by abdominal rigidity, rebound tenderness, and guarding—clinical features that strongly suggest peritoneal irritation and mandate urgent evaluation for intra-abdominal pathology. 1

Core Physical Examination Findings

The classic peritoneal signs include:

• Abdominal rigidity - This is the most specific finding and strongly suggests peritonitis, representing involuntary muscle contraction of the abdominal wall in response to peritoneal inflammation 1, 2
• Rebound tenderness and guarding - Present in 82.5% of patients with peritonitis, these findings reflect peritoneal irritation where pain worsens when pressure is suddenly released from the abdomen 1
• Abdominal pain and tenderness - Occurs in 74-95% of patients with peritonitis, typically diffuse in distribution 1, 2
• Decreased or absent bowel sounds - Results from developing ileus secondary to peritoneal inflammation 1, 2

Associated Systemic Signs

Peritoneal signs are frequently accompanied by systemic manifestations of inflammation:

• Tachycardia - Observed in 62.5% of patients as part of the systemic inflammatory response 1, 2
• Fever - Temperature greater than 38.5°C is present in 38% of cases 1, 2
• Hypotension - Indicates progression to septic shock and represents a critical finding requiring immediate intervention 1
• Tachypnea - Part of the systemic inflammatory response to peritoneal infection 1

Gastrointestinal Manifestations

• Nausea and vomiting - Reported in 35% of patients with peritonitis 1
• Absence of defecation and ileus symptoms - Associated with peritoneal inflammation 1
• Abdominal distension - Seen in 6.6% as an isolated finding, more commonly part of the overall presentation 1, 2

Critical Clinical Pitfalls

• Delayed development of signs - Peritoneal signs may take several hours to develop, particularly in small bowel injury, making serial examinations essential for accurate diagnosis 1
• Masked presentation - Physical signs may be subtle or completely masked by distracting injuries, head injuries, spinal cord injuries, or abdominal wall trauma 1
• "Pain out of proportion to examination" - This atypical presentation may occur in early peritonitis, making diagnosis challenging and requiring high clinical suspicion 1
• Time-sensitive diagnosis - Delayed diagnosis beyond 24 hours significantly increases mortality rates and the need for more invasive treatments 1, 2

Laboratory Abnormalities Supporting Peritoneal Signs

• Leukocytosis - Present in 40% of patients, often with left shift (band neutrophils >20%) 1, 2
• Elevated C-reactive protein (CRP) - Associated with peritoneal inflammation 1, 2
• Increased serum lactate - Indicates tissue hypoperfusion and sepsis 1
• Elevated procalcitonin (PCT) - Particularly significant in delayed presentations beyond 12 hours 1

Clinical Context and Pathophysiology

Peritoneal signs develop when the peritoneum—the serous membrane lining the abdominal cavity—becomes inflamed due to infection, perforation, or other irritants. 3 The peritoneum responds to insult through complex immunologic and inflammatory cascades, with the severity of signs correlating with the extent and duration of injury. 1, 2

The presence of peritoneal signs typically indicates secondary peritonitis, the most common form resulting from loss of integrity of the gastrointestinal tract (such as perforation), which requires both source control and antibiotic therapy. 3, 2