For a suspected hernia, should I order an abdominal ultrasound or an abdominal wall ultrasound?

Imaging for Suspected Hernia: Abdominal Wall Ultrasound vs Abdominal Ultrasound

For a suspected hernia, order an abdominal wall ultrasound, not a general abdominal ultrasound—the abdominal wall must be specifically targeted to evaluate the muscular defect, hernia contents, and any complications. 1, 2

Why Abdominal Wall Ultrasound is the Correct Order

The key distinction is anatomic specificity: An "abdominal ultrasound" typically refers to evaluation of intra-abdominal organs (liver, gallbladder, kidneys), while an "abdominal wall ultrasound" specifically targets the layers of the abdominal wall where hernias occur. 3

Advantages of Abdominal Wall Ultrasound

• Ultrasound of the abdominal wall is accurate, non-invasive, relatively inexpensive, and readily available for diagnosing abdominal wall hernias. 3
• It can identify hernias in patients with abdominal pain but no palpable mass, confirm questionable masses, and distinguish hernias from other pathologies. 3
• High-resolution ultrasound with high-frequency probes allows examination in a physiological manner and can detect the precise location and extent of muscular defects. 4, 5
• Point-of-care ultrasound (POCUS) is useful for evaluating patients with suspected hernias. 1

Clinical Scenarios Where Ultrasound is Most Valuable

• Patients with abdominal pain without a palpable hernia 3
• Patients with a palpable mass of questionable etiology 3
• Post-operative patients with inordinate pain or excessive swelling 3
• Inguinal hernias, where ultrasound has emerged as the most convenient imaging tool due to portability and absence of radiation 6

When to Escalate to CT Imaging

While ultrasound is excellent for initial evaluation, CT with IV contrast becomes necessary in specific situations:

Indications for CT Over Ultrasound

• Suspected internal hernias, which cannot be diagnosed clinically and require CT imaging 1, 2
• Suspected complications including incarceration, strangulation, bowel obstruction, or ischemia 7
• Post-bariatric surgery patients, where CT with both oral and IV contrast is mandatory due to altered anatomy 1, 2
• When ultrasound is equivocal or negative but clinical suspicion remains high 2
• Complex or large hernias requiring detailed pre-operative planning 7

CT Protocol Specifications When Needed

• Scan abdomen AND pelvis (not just abdomen) to capture full extent of potential hernias 1
• Use IV contrast to assess vascular perfusion and detect bowel ischemia or strangulation 1
• Use multiplanar reconstructions to increase accuracy in locating transition zones and hernia defects 1
• Avoid oral contrast in suspected high-grade bowel obstruction as it delays diagnosis 1

Special Population Considerations

• In pregnant patients with suspected hernias, ultrasound is the first-line imaging modality, followed by MRI if necessary, to avoid radiation exposure 8, 1, 7
• In children with suspected hernias, ultrasound is preferred as the initial imaging modality 8

Critical Pitfalls to Avoid

• Ordering a general "abdominal ultrasound" instead of specifically requesting "abdominal wall ultrasound"—the radiologist needs to know to focus on the wall layers and muscular defects 3, 4
• Assuming a negative ultrasound rules out hernia in post-bariatric surgery patients—maintain low threshold for CT or diagnostic laparoscopy if symptoms persist 1, 2
• Missing internal hernias by relying solely on ultrasound—these require CT for diagnosis 2
• Failing to demonstrate intraperitoneal communication through a muscular defect on imaging, which can lead to misdiagnosis of hernias as masses or cysts 4