Gallbladder sludge, also called biliary sludge, is a mixture of cholesterol crystals, calcium bilirubinate granules, and mucus that precipitates from bile that has been stagnant too long. On ultrasound, sludge appears as low-level, non-shadowing echoes that layer in the dependent portion of the gallbladder and move slowly when the patient changes position, unlike gallstones which move more readily. Sludge can occur during prolonged fasting, pregnancy, rapid weight loss, critical illness, or with certain medications. While sludge itself can sometimes resolve on its own, it is considered a precursor to gallstone formation and can occasionally cause symptoms similar to gallstones, including biliary colic and pancreatitis.
Sonography Term