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

Initial Approach to Abdominal Pain Assessment

The initial approach to a patient with abdominal pain requires a detailed history focusing on pain characteristics (onset, location, quality, severity, timing, aggravating/alleviating factors), thorough physical examination, appropriate laboratory tests, and targeted imaging based on pain location, with CT abdomen and pelvis with IV contrast being the preferred initial imaging modality for nonlocalized abdominal pain in adults. 1

History Taking - Key Elements

• Pain characteristics:

  • Location: Guides differential diagnosis (e.g., RLQ pain suggests appendicitis)
  • Onset: Sudden vs. gradual
  • Quality: Sharp, dull, cramping, burning
  • Severity: Using pain scale (1-10)
  • Timing: Constant vs. intermittent, relationship to meals
  • Aggravating/alleviating factors: Food, position changes, medications

• Associated symptoms:

  • Change in bowel habits (constipation may suggest obstruction) 1
  • Nausea/vomiting
  • Fever
  • Urinary symptoms
  • Weight loss

• Warning signs requiring urgent attention:

  • Severe pain out of proportion to physical exam findings (suspect mesenteric ischemia) 1
  • Pain with hypotension or shock
  • Rigid abdomen
  • Tachycardia (most sensitive sign of surgical complications) 1

Physical Examination

• Vital signs: Tachycardia, hypotension, fever
• General appearance: Distress level, positioning
• Abdominal examination:
  • Inspection: Distension, visible peristalsis, surgical scars
  • Auscultation: Bowel sounds (hyperactive, hypoactive, absent)
  • Percussion: Tympany, dullness, fluid wave
  • Palpation: Tenderness, guarding, rebound, rigidity, masses
• Rectal examination: For blood, masses, tenderness
• Pelvic examination: In women with lower abdominal pain

Laboratory Tests

Essential laboratory tests include:

• Complete blood count
• Comprehensive metabolic panel
• C-reactive protein (CRP) and/or procalcitonin
• Serum lactate levels
• Blood gas analysis
• Urinalysis
• Pregnancy test in women of childbearing age 1

Note: High CRP levels can predict complications, but normal CRP doesn't rule out serious pathology 1

Imaging Studies

Selection based on pain location and suspected diagnosis:

• Right upper quadrant pain:

  • Ultrasonography (first-line for gallbladder pathology) 1

• Right or left lower quadrant pain:

  • CT abdomen/pelvis with IV contrast (>95% sensitivity for appendicitis and diverticulitis) 1

• Suspected bowel obstruction or mesenteric ischemia:

  • CT with IV contrast (has replaced plain radiography) 1

• Pregnant patients:

  • Ultrasound as first-line (sensitivity 96.7%, specificity 85.7%)
  • MRI without contrast if ultrasound inconclusive 1

• Suspected mesenteric ischemia:

  • CT Angiography (CTA) without delay (every 6-hour delay doubles mortality)
  • Include arterial and venous phases
  • Avoid oral contrast 1

Special Considerations

Surgical Abdomen

Early surgical consultation is recommended when a surgical abdomen is suspected. Mandatory surgical exploration without delay is necessary in patients with signs of shock and multi-organ failure 1

Mesenteric Ischemia

• Nearly 50% of patients with embolic acute mesenteric ischemia have atrial fibrillation
• One-third have prior history of arterial embolus
• Non-occlusive mesenteric ischemia (NOMI) often associated with cardiac failure or recent surgery 1

Chronic Abdominal Pain

• Differentiate organic disease from functional disorders
• Avoid repetitive testing once functional pain is established
• Consider psychological support (e.g., cognitive therapy) with pharmacological options 2

Functional Pain Management

• Self-management strategies, neuromodulation, and brain-gut behavior therapies
• Baseline therapy with breathing techniques and low-dose tricyclic antidepressants or serotonin noradrenergic reuptake inhibitors
• Cognitive behavioral therapy for those with insight into how thoughts, feelings, and behaviors relate to pain
• Hypnotherapy for those with visceral hypersensitivity 3

Management Principles

• Correction of fluid and electrolyte abnormalities
• Low molecular weight heparin for thromboprophylaxis in hospitalized patients
• Antibiotics only when infection is suspected or confirmed (clinical improvement expected within 3-5 days) 1

Pitfalls to Avoid

1. Overlooking serious conditions: Pain out of proportion to exam findings should prompt consideration of mesenteric ischemia
2. Delayed imaging: Every 6-hour delay in CTA for suspected mesenteric ischemia doubles mortality
3. Inappropriate use of oral contrast: Not indicated and potentially harmful in suspected mesenteric ischemia
4. Relying solely on normal inflammatory markers: Normal CRP doesn't rule out complications
5. Missing atypical presentations: Elderly patients may present with atypical symptoms

By following this systematic approach to abdominal pain assessment, clinicians can efficiently identify life-threatening conditions requiring urgent intervention while appropriately managing less acute presentations.