Kidney stones typically form in the kidney and leave the body in the urine stream. A small stone may pass without causing symptoms. If a stone grows to more than 5 millimeters it can cause blockage of the ureter resulting in severe pain in the lower back or abdomen. A stone may also result in blood in the urine, vomiting, or painful urination. It is estimated that nearly 50 million people worldwide suffer from kidney stones resulting in more than 13,000 deaths each year. Read more here.