Kidney & Ureteral Stones
Each kidneys is connected to the bladder by a long (10 inches), small tube called the ureter, which drain urine from the kidney down to the bladder. The normal diameter of the ureter is that of a cocktail straw. When blockage of the kidney occurs at the location where the ureter connects to the kidney, then it is termed "ureteropelvic junction obstruction" or UPJ Obstruction. When blockage at this level occurs, pressure builds up within the kidney because the urine can not drain. This back pressure will cause swelling or "hydronephrosis" of the kidney and if this continues for a long period of time, irreversible damage to the kidney will occur. Certain factors such as a urinary tract infection, can cause accelerated damage to the kidney.
Causes / Risk factors
UPJ obstruction is usually a condition from birth however, it may not cause symptoms or cause problems until adulthood. It is the most frequently diagnosed cause of urinary blockage in children, and is usually diagnosed with a ultrasound study which show a dilated kidney or portion of the kidney where the urine drains into, called the renal pelvis.
Adult UPJ obstruction becomes symptomatic later in life, and can mimic other diseases. It is not unusual for the diagnosis to be difficult to be made. Many times it is discovered when x-rays are done for other reasons. Often it is due to an extra blood vessel that goes to the lower part of the kidney. As our body changes shape as we age, the kidney may drop slightly and cause the ureter to kink off over the blood vessel. Other causes include scar tissue from kidney stones, trauma, urinary tract infections, and prior surgery.