Black bile stones are composed of:: (A) Calcium bilirubinate stones, (B) Cholesterol monohydrate stones, (C) Calcium monohydrate stones, (D) Cholesterol bilirubinate stones
Answer is A. There are cholesterol stones and pigment stones. Cholesterol gallstones usually contain >50% cholesterol monohydrate. Pigment stones are composed primarily of calcium bilirubinate; they contain <20% cholesterol. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Pages 2616-17