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

Initial Workup for Right Lower Quadrant Abdominal Pain

CT of the abdomen and pelvis is the recommended initial imaging modality for adults presenting with right lower quadrant pain, with a sensitivity of 95% and specificity of 94% for diagnosing appendicitis and other causes of right lower quadrant pain. 1

Clinical Assessment

Before imaging, the following assessments should be performed:

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

Imaging Algorithm

Standard Adult Patients:

1. CT abdomen and pelvis with IV contrast (first-line)

   • Sensitivity: 95%, Specificity: 94% 1
   • Excellent for detecting appendicitis and alternative diagnoses
   • Oral contrast may be used based on institutional preference
   • Low-dose CT protocols can reduce radiation exposure while maintaining diagnostic accuracy 1

2. Ultrasonography (alternative in specific situations)

   • Consider as initial imaging in:
     • Young patients where radiation exposure is a concern
     • Pregnant patients
     • When CT is contraindicated
   • Limitations: operator-dependent, lower visualization rates of appendix in North America (compared to Europe/Asia) 1
   • Should be followed by CT if results are inconclusive or negative 1

Special Populations:

• Pregnant patients:

  • Ultrasound first
  • MRI if ultrasound is inconclusive
  • CT only if absolutely necessary 2

• Immunocompromised patients:

  • Lower threshold for immediate CT imaging
  • May present with atypical symptoms
  • Higher risk for serious pathology including intra-abdominal abscess 2, 3

• Elderly patients:

  • Lower threshold for CT imaging
  • Clinical signs may be unreliable
  • Higher risk for serious pathology 2

Differential Diagnosis

Right lower quadrant pain can indicate numerous conditions beyond appendicitis 4:

• Common causes:

  • Appendicitis (most common surgical cause)
  • Ileocecal inflammation/infection
  • Right-sided diverticulitis
  • Urolithiasis
  • Inflammatory bowel disease
  • Gynecological conditions (in women)

• Less common causes:

  • Malignancies
  • Epiploic appendagitis
  • Omental infarction
  • Mesenteric adenitis
  • Typhlitis (especially in immunocompromised patients) 3

Potential Pitfalls

• Delaying imaging in elderly patients who may present with atypical symptoms
• Missing gynecologic causes in women of reproductive age
• Overlooking serious pathology in immunocompromised patients
• Failing to recognize sepsis early 2
• Attributing all symptoms to a single cause without considering the full differential diagnosis

Management Considerations

Once imaging is completed and diagnosis established:

• Appendicitis: Surgical consultation for appendectomy or antibiotics-first approach in uncomplicated cases
• Abscesses: Percutaneous drainage for collections >3 cm plus antibiotics; smaller abscesses may be treated with antibiotics alone 2
• Inflammatory conditions: Appropriate medical therapy based on specific diagnosis
• Pain management: Multimodal analgesia with scheduled acetaminophen and NSAIDs as first-line therapy 2

The American College of Radiology Appropriateness Criteria strongly supports CT abdomen and pelvis as the imaging modality of choice for evaluating right lower quadrant pain in adults, with ultrasound serving as an alternative in specific patient populations 1.