What is the approach to a patient presenting with abdominal pain?

Approach to Abdominal Pain

The optimal approach to abdominal pain requires a systematic evaluation based on pain location, with CT scan of the abdomen and pelvis with IV contrast being the imaging modality of choice for most presentations, while ultrasonography should be used first for right upper quadrant pain. 1

Initial Clinical Assessment

History

• Pain characteristics:

  • Location: Helps narrow differential diagnosis
  • Onset: Sudden (perforation, volvulus) vs. gradual (inflammatory)
  • Quality: Sharp, dull, cramping
  • Severity: Out of proportion to exam findings suggests mesenteric ischemia 1
  • Timing: Constant vs. intermittent
  • Aggravating/alleviating factors

• Associated symptoms:

  • Vomiting: Suggests obstruction, especially if bilious
  • Fever: Indicates infectious/inflammatory process
  • Change in bowel habits: Constipation suggests obstruction 2
  • Urinary symptoms: May indicate urologic cause

Physical Examination

• Vital signs: Tachycardia, hypotension, fever
• Abdominal inspection: Distension suggests obstruction 2
• Auscultation: Hyperactive or absent bowel sounds
• Palpation: Location of tenderness, guarding, rebound tenderness
• Percussion: Tympany (gas) vs. dullness (fluid/mass)
• Rectal examination: For blood, masses, tenderness

Laboratory Testing

• Complete blood count: Leukocytosis suggests inflammation/infection
• Electrolytes: Identify metabolic disturbances
• Liver enzymes: For hepatobiliary pathology
• Inflammatory markers: ESR and CRP (elevated CRP is a significant predictor of hospital admission) 1, 3
• Urinalysis: For urologic causes
• Pregnancy test: In women of childbearing age

Imaging Based on Pain Location

Right Upper Quadrant Pain

• First-line: Ultrasonography (highest appropriateness rating) 2, 1
  • Excellent for gallbladder pathology, hepatic lesions
  • High sensitivity (96.7%) for abscesses 1

Right Lower Quadrant Pain

• First-line: CT with IV contrast 2, 1
  • Sensitivity >95% for appendicitis
  • Consider ultrasound first in pregnant patients or young patients 1

Left Lower Quadrant Pain

• First-line: CT with IV contrast 2, 1
  • High sensitivity for diverticulitis (>95%)
  • Detects complications like abscess formation

Diffuse Abdominal Pain

• First-line: CT with IV contrast 1
  • Best for detecting bowel obstruction, mesenteric ischemia
  • For suspected bowel obstruction, CT has replaced plain radiography 2, 4

Special Considerations

• Pregnant patients: Ultrasound first, then MRI without contrast if needed 1
• Renal insufficiency: Consider MRI without contrast 1
• Suspected mesenteric ischemia: CT angiography without delay (every 6-hour delay doubles mortality) 1

Important Clinical Pitfalls

1. Do not rely on plain radiographs for most abdominal pain evaluations - they have limited diagnostic value and have been largely replaced by CT and ultrasound 2, 1, 4

2. Do not delay imaging for suspected mesenteric ischemia - CT angiography should be performed immediately 1

3. Do not miss atypical presentations in elderly patients who may have minimal symptoms despite serious pathology

4. Do not overlook gynecological causes in women of childbearing age

5. Do not assume normal laboratory values rule out serious pathology - clinical assessment remains paramount 1

Management Principles

• Fluid resuscitation: Correct fluid and electrolyte abnormalities 1
• Pain control: Appropriate analgesia does not mask important findings
• Thromboprophylaxis: Low molecular weight heparin for hospitalized patients 1
• Antibiotics: Only when infection is suspected or confirmed 1
• Abscess management: Small abscesses (<3cm) may respond to antibiotics alone; larger ones typically require drainage 1

By following this systematic approach based on pain location and utilizing appropriate imaging modalities, clinicians can efficiently diagnose and manage patients presenting with abdominal pain.