Normally a balance of bile salts, lecithin and cholesterol keep gallstones from forming. If there are abnormally high levels of bile salts or, more commonly, cholesterol, stones can form. Symptoms usually occur when the stones block one of the biliary ducts. Gallstones may also be discovered upon ultrasound or abdominal CT study.
Reviewed last on: 6/8/2008
Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.