Gallstones are hard pigmented crystals that form in the gallbladder where bile is stored. They are composed of a variable mix of cholesterol, bilirubin, and calcium, and can be as small as a grain of sand to bigger than a golf ball. Gallstones usually remain in the gallbladder, but they can also get stuck in the cystic duct (the tube leading from the gallbladder to the intestines) or in one of the other bile ducts. Many people with gallstones don’t experience symptoms. However, gallstones can cause symptoms on their own—such as colicky pain, or when they lead to inflammation in the gallbladder or ducts. Another complication of gallstones is pancreatitis, when the duct leading from the pancreas to the intestines becomes blocked.