There, they can sometimes become infected leading to serious kidney infection called pyelonephritis. When kidney stone passes from the urine collecting system within the kidney into the ureter, it can act like a dam. preventing easy flow of urine from the kidney into the bladder. This causes urine to back up, increasing pressure and swelling within the kidney.
Pain from a kidney stone can be excruciating, particularly as the stone is passing through the ureter. Kidney stone pain of this type is referred to as renal colic and its intensity is often described as akin to the pain of childbirth. The pain often begins in the back or flank of the side of the low back. It may radiate to the front of the abdomen and, in males, may cause testicular or scrotal pain. The pain is often intermittent in waves causing the affected individual to writhe or move constantly to find a comfortable position. There can be associated nausea, vomiting and sweating. The intense pain can be continuous or it can wax and wane as the stone passes toward the bladder. Often, in between the intense pain phase, there remains a dull ache in the back or flank. Once the stone passes into the bladder, the obstruction is relieved, urine can flow freely and the pain resolves. The dull flank ache can remain for a few hours or days after the stone has passed. Since the urethra is much wider than the ureter, passing the stone while urinating is usually not an issue and most patients cannot tell when they have eliminated the stone from their bladder. The quantity and severity of pain is not related to the size of the stone but rather the amount of obstruction and kidney swelling present. Sometimes, there can be blood visible in the urine as the kidney stone passes and irritates the lining of the urinary tract. Most often, the urine is clear to the naked eye and red blood cells are only visible in the urine when it