Gallstones enter the bile ducts and block the passage of bile. The gallbladder is located in the right upper abdomen and stores bile pigments that are secreted by the liver and ultimately meant to be released into the gastrointestinal tract. Gallstones are found most commonly in the gallbladder, but can also be found in the bile ducts of the liver. Although both sexes are affected, women are affected more often with 20% of those over 40 having gallstones.