What is the relationship of sludge to gallstones?
Sludge is a common term that is applied to an abnormality of bile that is seen with ultrasonography of the gallbladder. Specifically, the bile within the gallbladder is seen to be of two different densities with the denser bile on the bottom. The bile is denser because it contains microscopic particles, usually cholesterol or pigment, embedded in mucus. (The mucus is secreted by the gallbladder.) Over time, sludge may remain in the gallbladder, it may disappear and not return, or it may come and go. As discussed previously, these particles may be precursors of gallstones, and they occur often in some situations in which gallstones frequently appear, for example, rapid weight loss, pregnancy, and prolonged fasting.
Nevertheless, it appears that sludge goes on to become gallstones in only a minority of individuals. Just to make matters more difficult, it is not clear how often - if at all - sludge alone causes problems. Sludge has been blamed for many of the same symptoms as gallstones-biliary colic, cholecystitis, and pancreatitis, but often these symptoms and complications are caused by very small gallstones that are missed by ultrasonography. Moreover, it is possible that these gallstone-like symptoms and complications are actually caused by small gallstones that have passed through the bile ducts and into the intestine rather than the sludge itself. Thus, there is uncertainty about the significance of sludge.
It is clear, however, that sludge is not the equivalent of gallstones. The practical implication of this uncertainty is that unless an individual's symptoms are typical of gallstones, sludge should not be considered as the cause of the symptoms.