Gallbladder sludge, also known as biliary sand, biliary sediment, or thick bile, is a mixture of particulate matter and bile, normally seen as a liquid-liquid level in the gallbladder on ultrasound, corresponding to the precipitate of bile solutes.
The term biliary microlithiasis is occasionally used as a synonym for sludge, however this is not strictly correct. Microlithiasis refers to the tiny calculi (<3 mm) undetectable on normal transabdominal ultrasound. Sludge may include these microliths in its composition, but this is only one element of a variable mixture of crystals, proteinaceous debris, lysed cells and mucin 5.
These precipitates consist of cholesterol monohydrate crystals, calcium bilirubinate granules, calcium salts, and mucus secreted by the gallbladder 1.
Gallbladder sludge appears as a low amplitude homogeneous echoes, layering on the posterior wall, and frequently forming fluid-fluid level with anechoic bile above it.
- it moves slowly with changes in patient position
- sludge does not cause shadowing unless associated with gallstones 2
Sludge can get compacted forming a mass-like lesion referred to as tumefactive sludge 4:
- hypoechogenic well defined intraluminal mass
- no posterior acoustic shadowing
- no internal vascularity at color Doppler
- mobility is not always demonstrated, therefore, raising differentials with polyps or gallbladder carcinoma
- T1: high-signal
- T2: iso- to mild hyperintensity
- T1 C+ (Gd): no enhancement
- DWI/ADC: no diffusion restriction
- 1. Shaffer EA. Gallbladder sludge: what is its clinical significance?. Curr Gastroenterol Rep. 2003;3 (2): 166-73. Pubmed citation
- 2. Ferreira, Adilson Cunha et al. Fatores de risco clínicos e ultra-sonográficos relacionados à litíase vesicular assintomática em mulheres. Radiol Bras [online]. 2004, vol.37, n.2 [cited 2013-02-04], pp. 77-82 . Available from: . ISSN 0100-3984. http://dx.doi.org/10.1590/S0100-39842004000200004.
- 3. Catalano OA, Sahani DV, Kalva SP et-al. MR imaging of the gallbladder: a pictorial essay. Radiographics. 2008;28 (1): 135-55. Radiographics (full text) - doi:10.1148/rg.281065183 - Pubmed citation
- 4. Argha Chatterjee, Camila Lopes Vendrami, Paul Nikolaidis, Pardeep K. Mittal, Andrew J. Bandy, Christine O. Menias, Nancy A. Hammond, Vahid Yaghmai, Guang-Yu Yang, Frank H. Miller. Uncommon Intraluminal Tumors of the Gallbladder and Biliary Tract: Spectrum of Imaging Appearances. (2019) RadioGraphics. 39 (2): 388-412. doi:10.1148/rg.2019180164 - Pubmed
- 5. Elta GH. Sphincter of Oddi dysfunction and bile duct microlithiasis in acute idiopathic pancreatitis. (2008) World journal of gastroenterology. 14 (7): 1023-6. doi:10.3748/wjg.14.1023 - Pubmed
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