Gallstones. Illustration of gallstones in the gall bladder (green) and common bile duct. Gallstones are hard deposits of salts or cholesterol that form in the gall bladder when the chemical composition of bile is upset. They are most common in women, the elderly and the obese, and usually cause no symptoms unless one becomes stuck in the bile duct, which can lead to acute pain, jaundice, infection, and the formation of a liver abscess. If necessary the gall bladder may be surgically removed. Also shown here are the liver (brown), pancreas (yellow), small intestine (pink) and blood vessels (red and blue).