A ureteropelvic junction (UPJ) obstruction occurs where there is a blockage in one of the ureters, the tube that brings urine from the kidney to the bladder. The blockage causes a backup of urine that can result in kidney damage. UPJ is most often diagnosed in children born with a blockage, but can also occur in children and adults with scar tissue. UPJ obstruction that affects kidney function is treated with surgery.
