What is the initial evaluation and management approach for a patient presenting with generalized abdominal pain?

Initial Evaluation and Management of Generalized Abdominal Pain

For adults presenting with generalized abdominal pain, obtain CT abdomen/pelvis with IV contrast as the primary imaging modality after ensuring hemodynamic stability, as this changes diagnosis in 51-54% of cases and alters management decisions in 25-42% of patients. 1

Immediate Stabilization and Risk Stratification

Assess for hemodynamic instability first - check vital signs for fever, tachycardia, tachipnea, hypotension, and altered mental status, which indicate potential organ failure requiring immediate resuscitation 1.

• Establish IV access and initiate fluid resuscitation if signs of sepsis or shock are present 1
• Administer low-molecular-weight heparin for VTE prophylaxis in all patients with acute abdominal pain, as this population carries high thrombotic risk 1
• Correct electrolyte abnormalities and anemia promptly 1

Focused History - Key Discriminating Features

Look for these specific clinical indicators that guide diagnosis:

• Pain migration to right lower quadrant + fever + positive psoas sign strongly suggests appendicitis 1, 2
• Vomiting before pain onset makes appendicitis less likely 1, 2
• Constipation + abdominal distension strongly suggests bowel obstruction 1, 3
• Recent surgery or prior abdominal operations raises concern for adhesive small bowel obstruction (accounts for 55-75% of SBO cases) 1
• Age >60 years + atherosclerotic risk factors should prompt consideration of mesenteric ischemia 1

Laboratory Testing

Order these specific tests to narrow the differential:

• Complete blood count (leukocytosis suggests infection/inflammation) 4
• C-reactive protein (elevated in inflammatory conditions) 1, 4
• Hepatobiliary markers (AST, ALT, alkaline phosphatase, bilirubin) 4
• Lipase (for pancreatitis) 4
• Urinalysis (for urolithiasis, UTI) 4
• Pregnancy test in all patients with reproductive organs 4
• Lactate if concerned for bowel ischemia or sepsis 1

Imaging Strategy

CT abdomen/pelvis with IV contrast is the gold standard for generalized abdominal pain - it identifies pathology across multiple organ systems and outperforms clinical diagnosis 1, 4.

• Single-phase IV contrast-enhanced CT is sufficient; pre-contrast and delayed phases are unnecessary 1
• Do NOT delay CT for oral contrast - it delays diagnosis without improving accuracy and slows ED throughput 1
• Plain radiographs have limited utility and should generally be avoided, except when bowel obstruction is strongly suspected clinically 1

Alternative Imaging Based on Pain Localization:

• Right upper quadrant pain: Start with ultrasound (first-line for hepatobiliary disease) 1, 2, 3, 4
• Right or left lower quadrant pain: CT with IV contrast 1, 2, 3

Antibiotic Administration

Do NOT routinely administer antibiotics for undifferentiated abdominal pain 1.

Antibiotics are indicated only when:

• Intra-abdominal abscess is identified (>3 cm requires percutaneous drainage + antibiotics) 1
• Clinical signs of sepsis are present 1
• Specific infection is confirmed (cholecystitis, diverticulitis, etc.) 1

When antibiotics are needed, cover Gram-negative aerobic/facultative bacilli, Gram-positive streptococci, and obligate anaerobes according to local resistance patterns 1.

Pain Management

Provide early analgesia without compromising diagnostic accuracy - this does not interfere with clinical assessment 2.

Avoid opioids in chronic or functional abdominal pain - they cause narcotic bowel syndrome, dependence, gut dysmotility, and increased mortality 2.

Common Diagnostic Pitfalls to Avoid

• Do not obtain repeat CT scans without clear clinical indication - diagnostic yield drops from 22% on initial CT to 5.9% on fourth or subsequent CTs 1
• Elderly patients may have normal labs despite serious infection - maintain high suspicion and rely on imaging 1
• CT in patients with abdominal pain + diarrhea has low yield (11% management change) - use thoughtful approach 1
• Do not limit scan coverage based on symptoms - scanning only the symptomatic region misses pathology in 67% of abnormal cases 1

Differential Diagnosis Framework

The most common causes in ED patients with generalized abdominal pain are 1:

• One-third: No diagnosis established (nonspecific pain)
• One-third: Appendicitis
• One-third: Other documented pathology including:
  • Acute cholecystitis
  • Small bowel obstruction
  • Pancreatitis
  • Renal colic
  • Perforated peptic ulcer
  • Malignancy
  • Diverticulitis

When to Involve Surgery

Surgical consultation is needed for 1, 5:

• Signs of peritonitis (guarding, rigidity, rebound tenderness)
• Hemodynamic instability despite resuscitation
• Free air on imaging (perforation)
• Complete bowel obstruction
• Mesenteric ischemia
• Ruptured abdominal aortic aneurysm
• Failed conservative management of identified surgical pathology

The acute abdomen carries 2-12% mortality, increasing with every hour of delayed treatment - structured, rapid diagnosis and treatment significantly reduce morbidity and mortality 5.