From the Guidelines
Ultrasound is generally better than CT for viewing the gallbladder. According to the most recent and highest quality study 1, ultrasound is suggested as the initial imaging modality over CT for suspected acute cholecystitis or acute cholangitis in adults, children, and pregnant people. This is because ultrasound is reasonably accurate and useful in identifying gallstones, less costly, and more portable, and results are generally available in a timelier manner.
Key Points
- Ultrasound provides excellent visualization of gallbladder anatomy and pathology without radiation exposure.
- It can readily detect gallstones, gallbladder wall thickening, sludge, polyps, and acute cholecystitis.
- Ultrasound is more cost-effective, widely available, and can be performed quickly at the bedside.
- The physics behind ultrasound's effectiveness lies in how sound waves interact with the fluid-filled gallbladder and the acoustic shadowing created by gallstones.
- CT scans may be preferred when complications of gallbladder disease are suspected, such as pancreatitis, perforation, or when a wider assessment of surrounding structures is needed.
Recommendations
- For routine gallbladder assessment, ultrasound remains the superior and recommended initial imaging choice 1.
- CT may be used as a secondary imaging modality when complications of gallbladder disease are suspected or when a wider assessment of surrounding structures is needed.
From the Research
Comparison of Ultrasound and CT for Gallbladder Imaging
- Ultrasound is the initial imaging modality of choice for evaluating suspected acute gallbladder disorders, and is often sufficient for correct diagnosis 2.
- CT plays a vital role in the evaluation of acute gallbladder pathology, particularly in situations where ultrasound findings are equivocal, and is useful in assessing suspected complications of acute cholecystitis 2.
- Ultrasound is often the first imaging modality used to evaluate the gallbladder due to its ease of accessibility, low cost, lack of ionizing radiation, and excellent spatial resolution 3.
- CT is used as part of a broader evaluation of patient's abdominal pain if nongallbladder pathologies are also suspected 4.
Specific Advantages of Each Modality
- Ultrasound is the method of choice for detection of gallstones, with characteristic findings including a highly reflective echo, mobility of the gallstone, and marked posterior acoustic shadowing 5.
- CT is extremely valuable in the assessment of suspected complications of acute cholecystitis, such as emphysematous cholecystitis, hemorrhagic cholecystitis, and gallbladder perforation, which are often difficult to diagnose with sonography 2.
- Ultrasound can evaluate common pathologies including gallbladder polyps, tumefactive sludge, adenomyomatosis, and acute cholecystitis, and can be used with Doppler, microvascular flow imaging, and contrast-enhanced ultrasound for further assessment 3.
Clinical Considerations
- The choice of imaging modality may depend on the clinical presentation and suspected diagnosis, with ultrasound often being the initial choice for right upper quadrant pain and CT being used for more complex or equivocal cases 4.
- A holistic approach to gallbladder examination using ultrasound, including grey scale, Doppler, CEUS, elastography, and 3D, can provide a comprehensive evaluation of gallbladder pathology 6.