Initial Test for a Chronically Contracted Gallbladder
Abdominal ultrasound is the initial test of choice for evaluating a chronically contracted gallbladder. 1
Rationale for Ultrasound as First-Line Imaging
Ultrasound is universally recommended as the preferred initial imaging modality for suspected biliary disease, including chronic cholecystitis presenting as a contracted gallbladder. 1 The ACR Appropriateness Criteria and World Society of Emergency Surgery guidelines both strongly endorse ultrasound based on:
- Cost-effectiveness and wide availability 1
- Lack of ionizing radiation exposure 1
- High accuracy (96%) for detecting gallstones, which are present in the majority of chronic cholecystitis cases 1
- Ability to evaluate gallbladder wall thickness, pericholecystic fluid, and alternative diagnoses 1
- Shorter examination time compared to nuclear medicine studies 1
Key Ultrasound Features to Assess
When evaluating a contracted gallbladder on ultrasound, look for:
- Gallbladder wall thickness: Normal is ≤2-3 mm; thickening ≥3 mm suggests chronic cholecystitis 2, 3
- Presence or absence of gallstones or sludge 1
- Sonographic Murphy sign (focal tenderness over the gallbladder), though this has limited specificity 1
- Pericholecystic fluid (usually absent in chronic cholecystitis, unlike acute cholecystitis) 1, 4
Critical Diagnostic Considerations
The diagnosis of chronic cholecystitis is inherently difficult on anatomic imaging alone. 1, 4 The gallbladder may appear either contracted or distended in chronic cholecystitis, and a contracted appearance must be interpreted in clinical context 1, 4:
- In fasting patients, a contracted gallbladder may indicate pathology such as chronic cholecystitis 4
- In postprandial patients, gallbladder contraction is a normal physiological response to cholecystokinin release 4
- Patient fasting status is therefore essential information when interpreting ultrasound findings 4
When Ultrasound Findings Are Equivocal
If ultrasound shows a contracted gallbladder but findings are inconclusive for chronic cholecystitis, consider:
- Tc-99m cholescintigraphy with gallbladder ejection fraction measurement for functional assessment 1, 4
- Gallbladder ejection fraction <30-38% in a patient with typical biliary pain suggests functional gallbladder disorder or chronic cholecystitis 1, 4
- Cholescintigraphy has higher sensitivity (97%) and specificity (90%) than ultrasound for acute cholecystitis, but ultrasound remains first-line due to its ability to evaluate anatomy and alternative diagnoses 1
Common Pitfalls to Avoid
- Never interpret a contracted gallbladder in isolation—always correlate with clinical symptoms, fasting status, and other imaging findings 4
- A contracted gallbladder does not exclude gallstones, which may still be visible within the contracted lumen 4
- Wall thickening on ultrasound during contraction can mimic pathology: the normal contracted gallbladder wall shows three distinct layers that should not be mistaken for true wall thickening 5
- In patients >70 years or with risk factors, consider gallbladder cancer as a rare but important differential diagnosis for a contracted gallbladder 4
Limitations of Ultrasound
- Sensitivity for chronic cholecystitis ranges widely (26-100%) across studies, with specificity of 62-88% 1
- Ultrasound is less useful in critically ill patients where gallbladder abnormalities are common without true cholecystitis 1
- Power Doppler ultrasound showing wall vascularization can help distinguish acute from chronic cholecystitis (vascularization suggests acute inflammation) 6, though this is not routinely performed