How to diagnose a hernia when it's not palpable?

From the Guidelines

Diagnosing a non-palpable hernia typically requires imaging studies, with a CT scan being the gold standard for diagnosing diaphragmatic hernias, offering a sensitivity and specificity of 14–82% and 87%, respectively 1. When a hernia is not palpable, it can be challenging to diagnose, but imaging studies can help.

• A chest X-ray can be useful, especially if it shows suspicious findings such as an abnormal bowel gas pattern, an air-fluid level, or an abnormal lucency or soft tissue opacity with deviation of the mediastinum 1.
• However, the chest X-ray has a limited sensitivity of 2–60% for diagnosing left-sided hernias and 17–33% for right-sided hernias 1.
• A CT scan is more accurate in determining the presence, location, and size of the diaphragmatic defect and can evaluate intrathoracic complications of herniated abdominal organs 1.
• The CT scan can also show various radiological findings, such as diaphragmatic discontinuity, segmental non-recognition of the diaphragm, and the "Dangling diaphragm" sign 1.
• In cases where the nature of the thoracic contents is uncertain, a nasogastric tube located inside the herniated stomach can be diagnostic 1.
• It's essential to note that while other imaging modalities like ultrasound and MRI can be useful in certain situations, the CT scan is the most reliable method for diagnosing non-palpable hernias, particularly diaphragmatic hernias 1.

From the Research

Diagnosing a Hernia when it's not Palpable

When a hernia is not palpable, diagnosis can be more challenging. The following methods can be used to diagnose a hernia in such cases:

• Imaging tests such as CT scans 2, 3 and ultrasonic scanning 4, 5, 6 can be used to verify the diagnosis of a hernia.
• CT findings can be subtle or confusing, but familiarity with a broad range of imaging appearances can help make an early and specific diagnosis of abdominal hernia 2.
• Ultrasonic scanning can be recommended for verification of the diagnosis in both palpable and nonpalpable spigelian hernia 4.
• Dynamic ultrasound evaluation can confirm the presence of a hernia and demonstrate the movement of abdominal contents through a wall defect 5.
• Abdominal wall ultrasound is a valuable tool in the management of patients with unclear diagnosis of abdominal wall hernia, and can influence therapeutic decisions 6.

Imaging Modalities

The choice of imaging modality depends on the specific case and the availability of equipment. The following imaging modalities can be used:

• CT scans: can show hernias and the contents of the peritoneal sac, and can be used to diagnose unsuspected hernias and distinguish hernias from other masses 2, 3.
• Ultrasonic scanning: can be used to verify the diagnosis of a hernia, and can demonstrate the movement of abdominal contents through a wall defect 4, 5, 6.
• Dynamic ultrasound: can provide added value over computed tomography by clearly demonstrating the movement of abdominal contents through a wall defect 5.

Clinical Presentation

The clinical presentation of a hernia can vary, and may include:

• Pain: which can be the most common symptom, but may vary in intensity and character 4.
• Palpable hernia or hernial orifice: which can be masked by subcutaneous fat and an intact external aponeurosis 4.
• Persistent point tenderness in the spigelian aponeurosis with a tensed abdominal wall: which can suggest the diagnosis of a spigelian hernia 4.