What does a board‑like rigid abdomen indicate and how should it be managed as an emergency?

Abdominal Rigidity: Emergency Diagnosis and Management

A board-like rigid abdomen indicates peritonitis from hollow viscus perforation, bowel ischemia, or severe intra-abdominal infection requiring immediate surgical intervention after rapid resuscitation. 1

Immediate Clinical Significance

Abdominal rigidity represents involuntary contraction of the abdominal wall muscles in response to peritoneal inflammation, distinguishing it from voluntary guarding. 1 This finding suggests the presence of peritonitis and demands urgent evaluation for life-threatening intra-abdominal pathology. 1

The presence of diffuse abdominal rigidity with hemodynamic instability (hypotension, tachycardia, altered mental status) mandates immediate laparotomy without waiting for imaging studies. 2

Initial Assessment and Resuscitation

Hemodynamic Evaluation

• Check blood pressure, heart rate, mental status, and peripheral perfusion immediately upon presentation. 2
• Assess for signs of septic shock including hypotension, lactic acidosis, oliguria, and altered mental status. 1
• Look for systemic inflammatory response with fever, tachycardia, and tachypnea accompanying the rigidity. 1

Immediate Resuscitation

• Establish IV access and begin crystalloid resuscitation with at least 30 mL/kg within the first 3 hours if hypotension or sepsis signs are present. 2
• Target mean arterial pressure ≥65 mmHg with norepinephrine as first-line vasopressor if hypotension persists despite fluid resuscitation. 2
• Administer broad-spectrum IV antibiotics covering aerobic gram-negative organisms and anaerobes within the first hour of recognizing severe sepsis or septic shock. 2

Diagnostic Algorithm Based on Stability

For Hemodynamically Unstable Patients

Proceed directly to emergency laparotomy without delay if diffuse abdominal rigidity is present with shock, hypotension, or tachycardia. 2 Do not wait for imaging studies as this delays definitive source control and increases mortality. 1, 2

For Hemodynamically Stable Patients

• Obtain complete blood count, serum creatinine, and inflammatory markers (C-reactive protein, procalcitonin, lactates) to assess severity. 1
• Perform CT angiography of the abdomen and pelvis with IV contrast as the gold standard imaging modality. 1
• CT scan identifies the source of peritonitis, detects free air from perforation, assesses for bowel ischemia, and evaluates for abscesses or other complications. 1

In resource-limited settings where CT is unavailable, plain X-ray abdomen (upright and supine) combined with ultrasound can identify free air, bowel obstruction, and fluid collections cost-effectively. 1

Surgical Decision-Making

Indications for Immediate Surgery

• Diffuse peritonitis with hemodynamic instability 2
• Signs of shock, gangrene, or bowel perforation 2
• Free air on imaging with clinical peritonitis 1
• Bowel ischemia or necrosis 1

Operative Approach

Open laparotomy is recommended for unstable patients or those with diffuse peritonitis rather than laparoscopic exploration. 2 The goals of surgery include:

• Identifying and controlling the source of contamination 1
• Resecting non-viable bowel 1
• Performing damage control techniques in critically ill patients 1

Open Abdomen Management

For patients with severe sepsis, consider leaving the abdomen open to prevent abdominal compartment syndrome, particularly when fascial closure would create excessive tension. 1 Intra-abdominal pressure may be measured intraoperatively to guide this decision. 1

Critical Pitfalls to Avoid

Delayed Diagnosis

Do not over-rely on imaging when clinical suspicion is high—perform diagnostic laparoscopy if imaging is negative but rigidity persists. 2 Many patients in resource-limited settings present with unacceptable delay, reducing survival rates. 1

Medication-Induced Rigidity

Consider metoclopramide-induced extrapyramidal symptoms causing abdominal wall rigidity that mimics an acute abdomen, though this is rare. 3 This presents without true peritonitis signs (no rebound tenderness, normal bowel sounds, no systemic inflammatory response).

Inadequate Source Control

Late or incomplete surgical procedures severely worsen outcomes in intra-abdominal infections. 1 Ensure complete source control at the initial operation, with planned second-look laparotomy at 24-48 hours if bowel viability is questionable. 1

Fluid Overresuscitation

Avoid excessive crystalloid administration that can lead to abdominal compartment syndrome, particularly in patients requiring prolonged resuscitation. 1 Monitor for signs of intra-abdominal hypertension including decreased urine output, increased peak airway pressures, and hemodynamic instability. 1

Antibiotic Therapy

Initiate empiric broad-spectrum antibiotics immediately upon diagnosis, covering both aerobic gram-negative bacteria and anaerobes. 2 Continue antibiotics for 48 hours as prophylaxis in cases with intestinal strangulation or concurrent bowel resection. 4