What are acute peritoneal signs?

Acute Peritoneal Signs: Clinical Definition and Recognition

Acute peritoneal signs are physical examination findings indicating peritoneal inflammation, primarily consisting of significant abdominal tenderness on palpation, involuntary guarding (abdominal wall rigidity), and rebound tenderness, which strongly suggest intra-abdominal pathology requiring urgent intervention. 1, 2

Core Physical Examination Findings

The cardinal peritoneal signs include:

• Involuntary guarding and abdominal rigidity - the most reliable indicator of peritoneal irritation, representing involuntary muscle contraction of the abdominal wall 1, 2
• Rebound tenderness - pain elicited upon sudden release of palpation pressure, present in 74-95% of patients with peritonitis 2
• Diffuse abdominal tenderness - widespread pain on palpation across multiple abdominal quadrants 1, 2

Associated Clinical Features

Beyond the classic triad, patients with acute peritoneal signs commonly present with:

• Tachycardia - occurs in 62.5% of patients and should be considered the most sensitive early warning sign, particularly in post-bariatric surgery patients where classic peritoneal signs may be absent 1, 2
• Fever greater than 38.5°C - present in 38% of cases 2
• Decreased or absent bowel sounds - indicating ileus from peritoneal inflammation 2
• Abdominal distension - seen in 6.6% of patients, particularly with bowel obstruction or perforation 2

Critical Diagnostic Limitations

Clinical examination alone is unreliable and misclassifies approximately 50% of patients, particularly in specific populations. 3

Important caveats include:

• Obesity significantly impairs detection - classic peritoneal signs are frequently absent in patients with increased body habitus, making tachycardia the most reliable indicator 1
• Delayed presentation with bowel injury - small bowel perforations may take several hours to develop peritoneal signs because luminal contents have neutral pH, low enzymatic activity, and relatively low bacterial load 1
• Masked findings in trauma patients - distracting injuries, head trauma, spinal cord injuries, and intoxication can obscure peritoneal signs 1, 4
• Pregnancy alters presentation - normal pregnancy symptoms overlap with peritoneal signs, leading to delayed diagnosis 1

Hemodynamic Considerations

The presence of peritoneal signs mandates urgent surgical evaluation regardless of vital sign stability, as hemodynamic "stability" does not exclude significant ongoing hemorrhage. 5

• Patients may maintain normal blood pressure (mean 131 mmHg) and heart rate (mean 91 bpm) despite having 750-1500 mL or more of intraperitoneal blood 5
• Hypotension, hypoperfusion signs (lactic acidosis, oliguria, altered mental status) indicate advanced sepsis requiring immediate intervention 2
• The combination of fever, tachycardia, and tachypnea is a significant predictor of anastomotic leak or visceral perforation 1

Time-Critical Nature

Diffuse peritonitis with acute peritoneal signs requires emergency surgical intervention as soon as possible, with every 3 minutes spent in the emergency department equating to 1% increased death probability. 1, 3

• Patients with obvious diffuse peritoneal signs do not require additional imaging before surgical exploration 3
• Delay in diagnosis and treatment significantly increases mortality rates 2
• For penetrating trauma with peritonitis, median time from diagnosis to incision should be 40 minutes or less 5

When Serial Examination is Appropriate

For hemodynamically stable patients without acute organ failure, intervention may be delayed up to 24 hours only if appropriate antimicrobial therapy is given and serial clinical examinations every 3-6 hours are performed. 3

This conservative approach requires:

• Localized rather than diffuse peritoneal signs 3
• Hemodynamic stability without signs of shock 3, 2
• Absence of fever or controlled fever with antibiotics 3
• Ability to perform frequent reassessment by experienced surgical personnel 1, 3