Alternate Names : Ureteropelvic Junction Obstruction, PUJ Obstruction, Pelvo-Uretero Junction Obstruction
The renal pelvis is the structure that drains urine from the kidneys. The tube that carries the urine from the renal pelvis into the bladder is called the ureter. The narrow area where these two structures meet is called the ureteropelvic junction (UPJ). A blockage in the UPJ can inhibit the flow of urine.
What is going on in the body?
Blockage of the UPJ can be present from birth. It is a common urinary tract abnormality. Most of the time the problem appears in childhood. In some people, however, symptoms may not show up until after puberty. Obstruction can also result from a kidney stone lodged in the area or from injury.
In between 10 and 40 percent of cases, UPJ obstruction occurs on both sides of the body. Twenty to forty percent of children with this condition have a backflow of urine into the kidney.
What are the causes and risks of the condition?
UPJ obstruction can be caused by the following:
abnormalities in the muscles of the ureter
scar tissue in the ureter
compression of the UPJ by a blood vessel leading to the kidney
kinks in the ureter
fibrous bands around the ureter
external trauma, or injury to the body over the kidney area
injury during endoscopy or surgical procedures
There is some suspicion that the problem can be inherited. However, this has not been proven conclusively.