UPJ Obstruction

Basic Facts

  • Ureteropelvic junction (UPJ) obstruction is a blockage at the point where the urine drainage tube (ureter) connects to the hollow portion of the kidney (pelvis).
  • UPJ obstruction is an anatomical anomaly that impedes urine flow from the kidney and can remain undiagnosed if there are no symptoms.
  • The more severe the UPJ obstruction is, the more dangerous it becomes because backup of urine in the kidney can sometimes destroy the kidney.
  • Surgery to repair UPJ obstruction has a success rate of 70 to 95 percent, depending on the type of procedure and the severity of the initial obstruction.

Ureteropelvic junction (UPJ) obstruction is any abnormality that slows or blocks the flow of urine through the kidney pelvis, the funnel-shaped area between the hollow, middle part of the kidney and the urine-draining tube known as the ureter.


Symptoms of UPJ include:

  • Intermittent flank pain (pain in the back between the ribs and hips);
  • Recurrent urinary tract infections;
  • Blood in urine (hematuria);
  • Bulging or swelling in the abdomen; and
  • Kidney stones.


The congenital cause of UPJ obstruction appears to be an abnormality in the muscle fibers at the point where the ureter connects to the central part of the kidney pelvis. UPJ obstruction may also be caused by the growth of scar tissue at the top of the ureter, which narrows the passage.


One or more of the following tests may be used to help diagnose UPJ:

  • Neo-natal ultrasound;
  • X ray;
  • Computed Tomography (CT) scan;
  • Intravenous urography (also called intravenous pyelogram, or IVP);
  • Ultrasonography;
  • Diuretic renal scan;
  • Helical CT scan; or
  • Retrograde pyelography.


Treatment for UPJ obstruction is only necessary if a blockage significantly restricts urine flow or if a patient experiences persistent pain. Treatment options include:

  • Retrograde balloon dilation;
  • Retrograde fluoroscopic endopyelotomy;
  • Retrograde ureteroscopic endopyelotomy;
  • Antegrade endopyelotomy;
  • Open pyeloplasty; and
  • Laparoscopic pyeloplasty.
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