From the Guidelines
CT scan is the gold standard for diagnosing diaphragmatic hernias, with a sensitivity and specificity of 14–82% and 87%, respectively 1. When evaluating hernias, the choice of imaging modality depends on the specific clinical scenario and the suspected type of hernia.
- For diaphragmatic hernias, CT scan is the most accurate imaging modality, allowing for the evaluation of the diaphragmatic defect, herniated contents, and potential complications such as bowel obstruction or strangulation.
- Ultrasound can be useful for evaluating abdominal wall hernias, particularly for reducing hernias, but its effectiveness may be limited in obese patients or complex cases.
- MRI provides excellent soft tissue contrast and can be useful for characterizing hernia contents and complications, especially in pelvic floor hernias.
- The imaging choice should be guided by clinical presentation, suspected hernia type, available resources, and whether the evaluation is for diagnosis or pre-surgical planning. In emergency situations where bowel obstruction or strangulation is suspected, CT scans are particularly useful as they can quickly assess the entire abdomen 1. For epigastric pain, a double-contrast upper GI series can be beneficial for evaluating structural and functional abnormalities of the esophagus, stomach, and duodenum, and is the most useful test for diagnosing a hiatal hernia 1.
From the Research
Imaging Modalities for Hernia Evaluation
The best imaging modality for evaluating hernias can be determined by considering the following factors:
- Sensitivity and specificity of the imaging modality
- Availability and cost of the imaging modality
- Operator expertise
Comparison of Imaging Modalities
The following imaging modalities have been compared in various studies:
- Ultrasound (US)
- Computed Tomography (CT)
- Magnetic Resonance Imaging (MRI)
- Key findings from these studies include:
- US has been shown to be a convenient and accurate imaging tool for diagnosing inguinal hernia, with high sensitivity and specificity 2
- US is also useful in evaluating abdominal wall hernias, particularly in cases where physical examination is inconclusive 3
- CT and MRI can also be used to evaluate hernias, but may be limited by cost and availability 4
- MRI has been shown to be a valid diagnostic tool in patients with clinically uncertain herniations, with high positive predictive value 5
Advantages and Limitations of Each Modality
The advantages and limitations of each imaging modality are:
- US: advantages include portability, absence of radiation, and low cost; limitations include operator dependence and potential for false-negative findings 3, 2
- CT: advantages include high sensitivity and specificity; limitations include cost, availability, and radiation exposure 4, 5
- MRI: advantages include high positive predictive value and ability to evaluate complex hernias; limitations include cost, availability, and potential for false-negative findings 5
Recommendations
Based on the available evidence, US may be the preferred imaging modality for evaluating hernias, particularly in cases where physical examination is inconclusive, due to its high sensitivity and specificity, as well as its convenience and low cost 2. However, the choice of imaging modality ultimately depends on the specific clinical scenario and the availability of local expertise.