What is the appropriate workup for a patient presenting with abdominal pain?

Appropriate Workup for Abdominal Pain

The optimal workup for abdominal pain should include a thorough history focusing on pain characteristics, physical examination with attention to peritoneal signs, targeted laboratory testing, and imaging guided by pain location, with CT with IV contrast being the preferred imaging modality for nonlocalized abdominal pain. 1, 2

Initial Assessment

History - Key Elements to Assess

• Pain characteristics:
  • Onset, location, quality, severity, timing
  • Aggravating/alleviating factors
  • Migration of pain
• Associated symptoms:
  • Nausea, vomiting, changes in bowel movements
  • Fever, changes in urination
• Red flag symptoms requiring urgent attention:
  • Blood in vomit or stool
  • Unexplained weight loss
  • Persistent fever
  • Pain waking patient from sleep
  • Fainting or lightheadedness 2

Physical Examination

• Systematic approach:
  • Inspection: distension, visible peristalsis, surgical scars
  • Auscultation: bowel sounds (hyperactive, hypoactive, absent)
  • Percussion: tympany, dullness, fluid shifts
  • Palpation: tenderness, guarding, rebound tenderness, rigidity 2

Laboratory Testing

• Basic laboratory panel:

  • Complete blood count (CBC)
  • C-reactive protein (CRP) - elevated levels (OR = 6.24) strongly predict hospital admission 3
  • Comprehensive metabolic panel (electrolytes, renal function, liver enzymes)
  • Urinalysis
  • Lipase (for suspected pancreatitis)
  • Pregnancy test in women of reproductive age 2, 4

• Interpretation:

  • Patients with normal leukocyte count and CRP should be re-evaluated after 12 hours if symptoms persist 5
  • Leukocytosis and elevated CRP suggest inflammatory or infectious process

Imaging Studies

Selection Based on Pain Location

1. Nonlocalized abdominal pain:

   • CT abdomen and pelvis with IV contrast is the preferred initial imaging
   • Increases diagnostic certainty from 70.5% to 92.2%
   • Changes diagnosis in 49% of cases and management plans in 42% 1, 2

2. Right upper quadrant pain:

   • Ultrasonography is first-line (high sensitivity for gallbladder disease) 2, 5
   • If ultrasound is inconclusive, proceed to CT with IV contrast

3. Left upper quadrant pain:

   • Upright chest radiograph or plain abdominal film initially
   • CT with IV contrast if diagnosis remains unclear 5

4. Lower quadrant pain:

   • CT with IV contrast is recommended
   • For women of reproductive age, consider transvaginal ultrasound first to evaluate gynecological causes 1, 5

Special Imaging Considerations

• Suspected abscess:

  Modality	Sensitivity	Specificity
  Ultrasound	96.7%	85.7%
  CT	76.7%	91.4%
  MRI	90-95%	90-95%

• Suspected mesenteric ischemia:

  • CT angiography with IV contrast is essential 1
  • Non-contrast CT has limited value for mesenteric ischemia

• Pregnant patients:

  • Ultrasound first
  • MRI if ultrasound inconclusive
  • Avoid CT when possible 2, 4

Special Populations

Elderly Patients

• Often present with atypical symptoms
• Only 50% with acute diverticulitis have pain in lower quadrants
• Only 17% may present with fever
• 43% may not have leukocytosis
• Lower threshold for advanced imaging 2

Women of Reproductive Age

• Always perform pregnancy testing
• Consider gynecological causes:
  • Ectopic pregnancy
  • Pelvic inflammatory disease
  • Ovarian torsion
  • Ovarian cysts 2, 4

Common Pitfalls to Avoid

• Dismissing pain as functional without adequate workup
• Administering antibiotics without evidence of infection
• Delaying imaging in patients with significant pain
• Failing to consider extra-abdominal causes of pain
• Relying solely on laboratory tests without appropriate imaging
• Overlooking gynecological causes in women 2

When to Consider Surgical Consultation

• Peritoneal signs (rigid abdomen, severe tenderness, rebound)
• Abnormal imaging findings (OR = 6.47 for hospital admission) 3
• Hemodynamic instability
• Persistent severe pain despite conservative management
• Suspected bowel obstruction, perforation, or ischemia 2

When evaluating abdominal pain, remember that CT has been shown to significantly improve diagnostic accuracy and change management decisions in a large percentage of cases. While ultrasound is valuable for specific indications and in certain populations, CT with IV contrast remains the cornerstone of evaluation for nonlocalized abdominal pain.