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Biliary sludge: can ultrasound reliably detect the presence of crystals in bile?
L S Wilkinson1, T S Levine, D Smith
1Department of Radiology, Northwick Park Hospital, Harrow, UK.
Objective:
To determine the accuracy of routine gallbladder ultrasound in the detection of crystals in bile.
Methods:
Preoperative ultrasonography was performed in 40 patients undergoing elective cholecystectomy. Bile was aspirated at operation and examined microscopically for the presence and quantity of crystals.
Results:
Six patients had echogenic bile, five of whom had large numbers of crystals at microscopy, and one only a few crystals. Thirty-four patients had hypoechoic bile, nine had large numbers of crystals and 25 of these had few or no crystals at microscopy. For those patients with echogenic bile (hyper- or isoechoic) the sensitivity for detection of large numbers of crystals was 5/14 (35.7%) with a specificity of 25/26 (96%). However, if the bile was hypoechoic the sensitivity was 9/14 (65%).
Conclusion:
For those patients with echogenic bile, ultrasound is highly specific for the detection of crystals, although the sensitivity is low. By contrast, those patients with hypoechoic bile at ultrasound would need a further investigation to exclude the presence of crystals.