Overview of Kidney Stones
Very little of what we eat is retained by the bodymost is excreted. Sometimes, excreted material crystallizes into various types of stones. Bile can crystallize in the gallbladder and form gallstones. Material in the urine can form kidney stones, which may cause severe pain and bleeding in the urine (hematuria). Large kidney stones can block the part of the kidney that collects the urine (staghorn calculus). In some cases, the stones move from the kidney through the ureter (tube that connects the kidneys to the bladder) toward the bladder.
The ureter, which is a thin, muscular tube, may be blocked by a kidney stone. Having a stone block the ureter is like a tiny rock with sharp edges getting stuck in it. The kidney continues to filter and put out urine, which backs up behind the stone. The pressure created behind the stone may push the kidney stone along the ureter, which can cause severe pain and bleeding in the lining of the ureter. In some cases, the stone can completely block the flow of urine from the kidney. In time, most stones eventually move through the ureter into the bladder, where they are passed with the urine.