Can cholecystitis be seen on ultrasound?

Ultrasound Diagnosis of Cholecystitis

Yes, cholecystitis can be effectively visualized on ultrasound, which is recommended as the first-line imaging modality for suspected acute cholecystitis due to its high accuracy, availability, and lack of radiation exposure. 1

Ultrasound as First-Line Imaging

Ultrasound is the preferred initial diagnostic imaging test for several important reasons:

• The 2024 Infectious Diseases Society of America guidelines provide a conditional recommendation (very low certainty of evidence) for abdominal ultrasound as the initial diagnostic imaging modality for suspected acute cholecystitis 1
• The American College of Radiology Appropriateness Criteria specifically recommends ultrasound as the first choice for investigation of right upper quadrant pain and suspected biliary disease 1
• Ultrasound has reported accuracy of 96% for detection of gallstones 1
• Avoids radiation exposure compared to CT scanning
• Readily available and cost-effective
• Can identify other potential causes of right upper quadrant pain

Sonographic Features of Cholecystitis

Ultrasound can detect several key findings that support the diagnosis of cholecystitis:

1. Gallstones - Appear as echogenic structures with posterior acoustic shadowing, often mobile with patient positioning 1
2. Gallbladder wall thickening - Wall thickness >3mm is considered abnormal 1
3. Sonographic Murphy's sign - Tenderness when the ultrasound probe compresses directly over the gallbladder 1
4. Pericholecystic fluid - Appears as hypoechoic or anechoic regions around the gallbladder 1
5. Increased gallbladder diameter - Transverse diameter >5cm may indicate cholecystitis 1

Diagnostic Performance

While ultrasound is the recommended first-line imaging modality, its diagnostic performance has some limitations:

• Sensitivity for acute cholecystitis has been reported at 75.7%, which is lower than previously thought 2
• Sensitivity for chronic cholecystitis is even lower at 34.6% 2
• Sensitivity decreases with increasing time between ultrasound and surgical confirmation, falling below 50% after 140 days 2
• A meta-analysis showed that cholescintigraphy has better sensitivity (96%) and specificity (90%) than ultrasound (81% and 83%, respectively) for acute cholecystitis 1

Complicated Cholecystitis on Ultrasound

Ultrasound can also detect complications of cholecystitis:

• Hemorrhagic cholecystitis - May show complex fluid within the gallbladder lumen, though CT is more sensitive for this complication 3
• Emphysematous cholecystitis - Can show gas in the gallbladder wall or lumen
• Gangrenous cholecystitis - May show irregular wall thickening or membrane separation
• Perforation - Can sometimes be visualized as discontinuity in the gallbladder wall 4

When Additional Imaging Is Needed

If ultrasound findings are inconclusive or complicated cholecystitis is suspected:

• CT may be considered for further evaluation, especially if complications are suspected 1, 5
• CT has superior ability to assess pericholecystic inflammation in cases of acalculous cholecystitis 5
• MRI may be used in patients with equivocal ultrasound findings or to better visualize hepatic and biliary abnormalities 1
• Cholescintigraphy (HIDA scan) may be considered when ultrasound is inconclusive but clinical suspicion remains high 1

Clinical Implications

The finding of cholecystitis on ultrasound has important clinical implications:

• Predicts the difficulty grade of cholecystectomy, with the strongest correlation when ultrasound is performed within 27 days of surgery 2
• In high-risk surgical patients, ultrasound-guided percutaneous cholecystostomy may be considered as a temporizing measure 6

Ultrasound remains the cornerstone of initial imaging for suspected cholecystitis, but clinicians should be aware of its limitations and consider additional imaging when clinical suspicion is high despite negative ultrasound findings.