Ureteropelvic Junction Obstruction (UPJ Obstruction)
Ureteropelvic (ure·tero·-ˈpel-vik) junction obstruction (UPJO) is a blockage between the ureter and an area in the kidneys called the pelvis.
What is a Ureteropelvic Junction Obstruction?
Ureteropelvic (ure·tero·-ˈpel-vik) junction obstruction (UPJO) is a blockage between the ureter and an area in the kidneys called the pelvis. The pelvis is the center of the kidney. It is where urine collects before it moves to the ureters (the tubes that move urine to the bladder). This blockage can be caused by:
- the ureter being too narrow
- a blood vessel in the wrong position that narrows the ureter
It happens once in every 2,000 births and more often in males.
UPJO can also lead to other problems, such as swollen kidneys caused by a back-up of urine (hydronephrosis), low amniotic fluid, or underdeveloped lungs.
How is a Ureteropelvic Junction Obstruction Caused?
The cause of ureteropelvic junction obstruction is not known. In most cases, UPJO develops before a baby is born. It is caused by narrow ureters or a blood vessel that is in the wrong place. This makes it hard for urine to pass from the kidney into the ureter.
What are the Signs and Symptoms of a Ureteropelvic Junction Obstruction?
Signs of UPJO are seen on an ultrasound test. The most common sign is swollen kidneys caused by a blockage or back-up of urine. This is called hydronephrosis.
How is a Ureteropelvic Junction Obstruction Diagnosed?
UPJO will mostly likely be found during a prenatal ultrasound. More tests may be done after birth to confirm your baby’s diagnosis. Tests can include:
- Voiding cystourethrogram (VCUG): This is a special X-ray that looks at the urinary tract and bladder.
- Mercaptoacetyltriglycine renal scan (Lasix renal scan): This is a scan that shows how the kidneys look and work. It is done by injecting an isotope into your child’s vein and watching it as it travels through the kidneys and out the bladder.
How is a Ureteropelvic Junction Obstruction Treated?
In many cases, UPJO goes away on its own before your baby is born. You will have ultrasounds about every 4 weeks during your pregnancy to look for changes to the baby’s kidneys and the amount of amniotic fluid.
Most children with hydronephrosis after birth will not need surgery. If your baby has UPJO, more tests will be needed to find out if it is harming the kidneys. Surgery may be needed if the swelling gets worse, over time, or the kidney is being damaged. Your baby may have check-ups and tests to watch kidney function until the problem goes away on its own or surgery is done. The goal is for normal urine flow from the kidneys.
A blockage in the fetal kidney system can lead to low amniotic fluid. Amniotic fluid helps your baby’s lungs grow before they are born. When the fluid is too low, their lungs may not fully develop. If this happens, your baby may need special care after birth. In some cases, UPJO can cause permanent problems with the kidneys or lungs.
Most cases go away on their own before birth or in early childhood with no long-term problems. More serious cases may cause infections or damage to the kidneys. Surgery may be needed to remove the blockage. If the damage is not stopped, a kidney transplant may be the needed.