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

Initial Evaluation and Management of Abdominal Pain

The initial evaluation of abdominal pain should include a focused history, physical examination, appropriate laboratory tests, and targeted imaging based on pain location, with CT with IV contrast being the first-line imaging for nonlocalized abdominal pain. 1

History and Physical Examination

Key History Elements

• Pain characteristics: onset, location, quality, severity, timing, aggravating/alleviating factors 1
• Associated symptoms: fever, vomiting, diarrhea, constipation, urinary symptoms
• Past medical history: previous surgeries, known conditions (gallstones, diverticulitis)
• Medications: NSAIDs, antibiotics, opioids

Physical Examination Focus

• Vital signs: tachycardia, hypotension, fever (alarming signs requiring immediate attention) 1
• Abdominal examination: tenderness, guarding, rigidity, rebound tenderness
• Specific findings by location:
  • RUQ: Murphy's sign (gallbladder)
  • RLQ: McBurney's point tenderness (appendicitis)
  • LLQ: tenderness (diverticulitis)
  • Diffuse: peritonitis, bowel obstruction

Laboratory Testing

• Complete blood count (CBC)
• Comprehensive metabolic panel (CMP)
• C-reactive protein (CRP) and/or procalcitonin
• Serum lactate levels (for suspected mesenteric ischemia)
• Urinalysis
• Pregnancy test in women of childbearing age 1

Note: Normal white blood cell count does not exclude serious pathology and should not be relied upon solely for diagnosis 1

Imaging Selection Algorithm

Based on Pain Location:

1. Right Upper Quadrant Pain

   • Ultrasonography is first-line (sensitivity 96.7%, specificity 85.7%) 1
   • CT with IV contrast if ultrasound inconclusive

2. Right Lower Quadrant Pain

   • CT with IV contrast (first-line for suspected appendicitis) 1, 2
   • Ultrasound in pregnant patients or young women

3. Left Lower Quadrant Pain

   • CT with IV contrast (first-line for suspected diverticulitis) 2, 1

4. Nonlocalized Abdominal Pain

   • CT abdomen and pelvis with IV contrast 2, 1
   • Oral contrast may not be necessary and can delay diagnosis 2

5. Suspected Mesenteric Ischemia

   • CT Angiography without delay (arterial and venous phases)
   • No oral contrast (may be harmful) 1

Management Principles

Immediate Interventions

• Fluid resuscitation for hemodynamic instability 2
• Vasopressors if fluid resuscitation fails 2
• Early antibiotics within first hour for suspected sepsis 1, 3
• Pain management: opioid analgesics do not affect diagnostic accuracy 3

Specific Management Based on Diagnosis

• Antispasmodics for crampy pain, particularly when exacerbated by meals 1
• Antibiotics for confirmed infections (clinical improvement expected within 3-5 days) 1
• Correction of fluid and electrolyte abnormalities 1
• Low molecular weight heparin for thromboprophylaxis in hospitalized patients 1

Special Considerations

Pregnancy

• Ultrasound as first-line imaging 1
• MRI preferred over CT if ultrasound inconclusive 1
• Position with left lateral tilt to prevent aortocaval compression 1

Elderly Patients

• May present with atypical symptoms
• Higher risk for serious pathologies like mesenteric ischemia
• Consider CT earlier in the diagnostic algorithm 1

Sepsis Recognition

• Early recognition of sepsis is crucial for improved outcomes
• Warning signs: tachycardia, hypotension, respiratory distress, decreased urine output 2, 1
• Elevated lactate levels should prompt aggressive management 2

Common Pitfalls to Avoid

1. Relying solely on laboratory values to rule out serious pathology
2. Delaying imaging in patients with concerning clinical features
3. Overlooking extra-abdominal causes of abdominal pain
4. Failing to recognize early signs of sepsis
5. Using plain radiographs as primary imaging (limited value in non-traumatic abdominal pain) 1
6. Delaying antibiotics in suspected sepsis
7. Withholding necessary imaging in pregnant patients due to radiation concerns 1