Should an ultrasound be ordered for a patient with noted abdominal pain?

Diagnostic Imaging for Abdominal Pain

Diagnostic imaging should be ordered for patients with abdominal pain when the history, physical examination, and laboratory testing do not identify an underlying cause and serious pathology remains a clinical concern. 1

Imaging Selection Based on Pain Location

Right Upper Quadrant Pain

• Ultrasonography is the initial imaging study of choice for patients with right upper quadrant pain, particularly when cholecystitis is suspected 1
• If ultrasonography is equivocal, cholescintigraphy or CT may be considered as follow-up studies 1

Right or Left Lower Quadrant Pain

• CT with contrast media is the recommended initial imaging study for evaluating right or left lower quadrant pain 1
• For suspected appendicitis, CT of the abdomen and pelvis with contrast media is the preferred imaging modality 1
• For suspected diverticulitis, CT of the abdomen and pelvis with contrast media is recommended, with a sensitivity greater than 95% 1

Nonlocalized Abdominal Pain

• CT of the abdomen and pelvis with contrast media is typically the imaging modality of choice for diffuse or nonlocalized abdominal pain when serious pathology is suspected 1
• A prospective study found that CT results altered the leading diagnosis in 49% of patients and changed the management plan in 42% of patients with non-traumatic abdominal pain 1

Special Patient Populations

Women of Reproductive Age

• Beta human chorionic gonadotropin (β-hCG) testing should be obtained before ordering diagnostic imaging in premenopausal women to narrow the differential diagnosis and avoid radiation exposure to a potential embryo or fetus 1, 2
• Transvaginal or transabdominal ultrasonography of the pelvis is the recommended imaging study for reproductive-aged females with suspected gynecologic etiology or positive β-hCG test 1, 3

Pregnant Patients

• Ultrasonography is the first-line imaging modality for pregnant patients with abdominal pain (rated 8/9 in appropriateness) 1, 4
• MRI without contrast media is the second-line imaging choice for pregnant patients (rated 7/9 in appropriateness) 1, 4
• CT should only be used after other studies without ionizing radiation have been attempted and if serious pathology remains a concern 1

Radiation Considerations

• The widespread use of CT raises concerns about patient exposure to ionizing radiation 1
• Abdominal CT exposes patients to approximately 10 mSv of radiation, compared to the annual background radiation dose of 3 mSv in the United States 1
• Strategies to reduce radiation exposure include:
  • Using ultrasonography as an initial study before obtaining CT 1
  • Using low-dose CT protocols when appropriate 1
  • Considering MRI as an alternative to CT to avoid ionizing radiation 1

Common Pitfalls to Avoid

• Relying on conventional radiography as the sole imaging modality for abdominal pain, as it has limited diagnostic value and rarely changes patient treatment 1
• Failing to obtain β-hCG testing in women of reproductive age before ordering imaging studies that involve radiation 1, 2
• Overuse of CT imaging without considering radiation exposure, particularly in young patients or those who may require multiple imaging studies over time 1
• Failing to consider alternative diagnoses when initial imaging is negative despite persistent symptoms 4

Conclusion

The decision to order imaging for abdominal pain should be based on the location of pain, clinical suspicion of serious pathology, and patient-specific factors. The American College of Radiology Appropriateness Criteria provide evidence-based guidance for selecting the most appropriate imaging study based on clinical presentation.