Children's Hospital Colorado

Ureteropelvic Junction Obstruction (UPJO)

What is ureteropelvic junction obstruction (UPJO)?

A ureteropelvic junction obstruction (UPJO) is an obstruction or blockage at the junction of the kidney and ureter. Under normal conditions, the kidneys filter the blood and remove waste in the form of urine. The urine then drains from the kidneys down through the ureters into the bladder. When a UPJO occurs, the amount of urine produced is more than the amount that can be drained through the ureter causing a ‘backup’ of urine. This in turn creates a collection of urine in the kidney, called hydronephrosis.

This illustration shows a kidney affected by ureteropelvic junction obstruction, which leads to hydronephrosis.

What causes UPJO?

The cause of UPJO is not well known, but abnormal tethering of the ureter or a narrowing of the ureter occurs during fetal development. The most common cause of an obstruction or blockage occurs while the child is still in the womb. UPJO is considered a congenital obstruction, meaning it is a condition that occurs at birth, or before birth.

Who gets UPJO?

The cause of a JPJO is not well known, and therefore there is no known prevention for this condition

Helpful resources:

Learn about the Department of Pediatric Urology at Children's Hospital Colorado.

What are the signs and symptoms of UPJO?

Usually, an ureteropelvic junction obstruction has no physical symptoms. It can sometimes be associated with urinary tract infections, as patients can experience flank pain, painful urination, irritability, fussiness, fever and/or foul-smelling urine.

What tests are used to diagnose UPJO?

A ureteropelvic junction obstruction is a congenital abnormality that can often be detected during pregnancy. It can be diagnosed during a prenatal ultrasound, however it may not show up until the child is older.

If your child is diagnosed prenatally, you may contact the Urology Department at Children's Hospital Colorado prior to, or immediately after, your child’s birth. If your child is not diagnosed at birth, contact Children’s Colorado Urology Department for further evaluation at the recommendation of your primary care physician.

How do doctors at Children’s Hospital Colorado make a diagnosis?

The diagnosis is made by renal ultrasound. Once the diagnosis is made, it is often necessary to perform regular ultrasounds to check on the progress of the hydronephrosis as it can resolve. In addition a MAG 3 renogram is needed to check on how the kidney is functioning and draining, and a VCUG study is required to evaluate whether there is any reflux of urine into the kidney.

How is a UPJO treated?

Treatment of a ureteropelvic junction obstruction usually requires an operation called a pyeloplasty. During a pyeloplasty surgery, the obstruction is removed and the ureter is reconnected to the kidney. This allows normal drainage to occur, however it can take some time for the kidney to fully drain. Sometimes a stent will be left in the ureter, which allows the repair to heal. This helps the ureter to continue to function correctly. Removal of the stent takes place in the operating room and usually occurs 4 to 6 weeks later. Radiology testing is done after the surgery to ensure that the operation has worked.

Why choose Children’s Hospital Colorado for your child’s UPJO treatment?

At Children’s Hospital Colorado, we have state of the art expertise in minimally invasive surgery and utilize this whenever appropriate. Our providers have extensive experience in medical management of hydronephrosis as well as moving forward appropriately with surgical intervention, if necessary. Our urology team is currently collecting research about hydronephrosis to ensure that current practices are the most up to date and efficient as possible.


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