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

Initial Workup for Abdominal Pain

The initial workup for a patient presenting with abdominal pain should include a focused history, physical examination, complete blood count, and targeted imaging based on pain location, with contrast-enhanced CT scan of the abdomen and pelvis being the first-line imaging modality for nonlocalized abdominal pain due to its near 100% sensitivity for many common causes. 1, 2

History and Physical Examination Elements

• Pain characteristics:

  • Location (quadrant-specific)
  • Onset (sudden vs. gradual)
  • Quality (sharp, dull, cramping)
  • Radiation
  • Severity
  • Timing (constant vs. intermittent)
  • Aggravating/alleviating factors

• Associated symptoms:

  • Fever (suggests infection/inflammation)
  • Nausea/vomiting
  • Changes in bowel habits
  • Urinary symptoms
  • Vaginal discharge/bleeding in women

• Key physical examination findings:

  • Vital signs (fever, tachycardia, hypotension)
  • Abdominal tenderness, guarding, rebound
  • Abdominal distension
  • Bowel sounds
  • Rectal examination
  • Pelvic examination in women

Laboratory Testing

• Complete blood count (CBC) - assess for leukocytosis
• Basic metabolic panel
• Liver function tests
• Lipase/amylase (if pancreatitis suspected)
• Urinalysis
• Pregnancy test (β-hCG) in all women of reproductive age 2

Imaging Studies

Nonlocalized Abdominal Pain

• First-line: Contrast-enhanced CT abdomen and pelvis

  • High sensitivity (near 100%) for many common causes 1, 2
  • Essential for immunocompromised patients 2
  • Particularly valuable when fever is present 1

• Alternative if CT contraindicated: MRI abdomen and pelvis

  • Comparable accuracy to CT for many intra-abdominal pathologies
  • Sensitivity of 100% for appendicitis and 86% for ovarian torsion 1
  • Preferred in pregnancy with inconclusive ultrasound 2

Localized Abdominal Pain

• Right upper quadrant pain:

  • First-line: Ultrasonography (88% sensitivity, 80% specificity for acute cholecystitis) 2

• Right lower quadrant pain (suspected appendicitis):

  • Adults: CT (97% sensitivity, 94% specificity) 1
  • Children: Ultrasound first (82% sensitivity, 94% specificity for all results) 1
  • Pregnant patients: Ultrasound first, then MRI if inconclusive 1, 2

• Left lower quadrant pain (suspected diverticulitis):

  • CT abdomen and pelvis (81% sensitivity vs. 61% for ultrasound) 1

• Pelvic pain in women:

  • Transvaginal ultrasound for suspected gynecologic etiology 2

Special Populations Considerations

Elderly Patients

• Lower threshold for advanced imaging
• May present with atypical symptoms
• Higher risk for serious pathology 2

Immunocompromised Patients

• Require lower threshold for CT imaging
• Clinical signs may be unreliable
• Higher risk for intra-abdominal abscess 1, 2

Pregnant Patients

• Ultrasound first approach
• MRI if ultrasound inconclusive
• Avoid radiation when possible 2

Common Pitfalls to Avoid

• Relying solely on clinical presentation (error rates of 34-68% for conditions like diverticulitis) 2
• Delaying imaging in high-risk populations (elderly, immunocompromised)
• Missing gynecologic causes in women of reproductive age
• Overlooking extra-abdominal causes of abdominal pain (thoracic, pelvic, metabolic)
• Using abdominal radiographs as primary imaging (low sensitivity, 49% for bowel obstruction, lower for other conditions) 1

When to Consider Surgical Consultation

• Peritoneal signs
• Bowel obstruction
• Suspected appendicitis
• Perforated viscus
• Mesenteric ischemia 1
• Abdominal aortic aneurysm

By following this structured approach to the initial workup of abdominal pain, clinicians can efficiently diagnose and manage patients while minimizing missed diagnoses of serious conditions.