What Is Ureterovesical Junction Obstruction?

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The ureterovesical junction (UVJ) is the area where the ureter—the thin tube that drains urine from your kidney—joins the bladder. When this area or "junction" becomes blocked, a condition called ureterovesical junction obstruction develops.

UVJ obstruction prevents urine from normally flowing into the bladder, where it is eventually released by urination. As a result, the urine backs up into the ureter and kidney, causing them both to become swollen and dilated.

This rare condition occurs when the fetal urinary tract system is developing in utero. It is usually diagnosed during a prenatal ultrasound and treated in early infancy.

Ureterovesical junction obstruction is more common in boys than girls and tends to only affect the left ureter and kidney.

The Urinary Tract System

Within your urinary tract system are the following four organs:

  • Two kidneys
  • Two ureters
  • Bladder
  • Urethra

The kidneys are bean-shaped organs located in the back of your abdomen, right below your ribcage.

Each kidney is attached to a long, thin tube called a ureter. The ureter propels urine from the kidney to the bladder where it is stored and eventually urinated out through the urethra.

Ureterovesical Junction Obstruction Symptoms

UVJ obstruction is often seen on a routine prenatal screening ultrasound while the baby is still growing and developing in the mother's womb.

The ultrasound will reveal a swollen kidney (called hydronephrosis) and a swollen ureter (called hydroureter). The obstruction can be monitored during the pregnancy, and then confirmed with additional imaging tests at birth.

In terms of symptoms, a baby born with UVJ obstruction generally has no symptoms.

That said, if not diagnosed early, or if the cause is acquired (not a developmental problem), children with UVJ obstruction may experience the following symptoms:

Causes

UVJ obstruction is usually congenital, which means it occurs during the development of a fetus's urinary tract system in the womb.

In some cases, the junction linking the ureter to the bladder is abnormally narrowed. In other cases, the obstruction occurs as a result of an abnormality in the way that the ureter grows into the bladder during development.

Less commonly, UVJ obstruction is acquired, meaning it occurs after birth.

Causes of acquired UVJ obstruction include:

  • Scar tissue
  • Severe untreated Infection
  • Benign (non-cancerous) polyp
  • Lodged kidney stone

Diagnosis

In order to confirm the diagnosis of UVJ obstruction after a baby is born (and to evaluate the severity or degree of the blockage), a variety of tests will be performed.

These tests may include:

Blood and Urine Tests

Your doctor will perform a blood test to evaluate your child's kidney function. They will also perform a creatinine clearance test, which measures the rate at which a waste product called creatinine is removed from the blood by the kidneys.

Renal Bladder Ultrasound

Using sound waves, a renal bladder ultrasound (RBUS) produces an outline of the kidneys and bladder. This way, the doctor can visualize the severity of the kidney swelling.

Mercapto-Acetyl-Triglycine MAG3 Renal Scan

The Mercapto-acetyl-triglycine MAG3 Renal Scan is a nuclear medicine test that allows your child's doctor to evaluate their kidneys' structure and function, and determine if an obstruction is present.

Prior to the test, your child will be injected with a solution called an isotope (mercapto-acetyl-triglycine) into their vein. This isotope travels to your child's kidneys and then drains out through their urine.

Voiding Cystourethrogram

With a voiding cystourethrogram (VCUG), your child will have a contrast dye injected in their bladder through a urinary catheter. Using X-ray pictures, your doctor can then see if the urine abnormally flows back ("refluxes") into the ureters and kidneys, instead of entering the bladder.

Magnetic Resonance Urography

A magnetic resonance urography (MRU) is performed in a magnetic resonance imaging (MRI) machine and uses magnetic waves (no radiation) to visualize your child's urinary tract system.

Since this test requires a urinary catheter and peripheral IV (and that your child lies face down for about 40 minutes), sedation may be needed.

Treatment

If UVJ obstruction is left untreated, the kidney and ureter can become so swollen that the function of the kidney becomes compromised. Children can develop symptoms then, such as flank pain and/or recurrent urinary tract infections.

The primary goal in treating a child's UVJ obstruction is to conserve the function of the kidney.

Ureteral Reimplantation

The mainstay treatment for UVJ obstruction is a surgical procedure called ureteral reimplantation. In this surgery, the abnormal part of the ureter that connects to the bladder is removed. The rest of the ureter is then reconnected to another part of the bladder.

This surgery, which is performed under general anesthesia, can be performed in different ways:

  • Open—a larger cut (incision) is made in the child's abdomen to visualize the bladder
  • Robotic laparoscopic—three very tiny incisions are made in the child's abdomen
  • Endoscopic (there are no incisions)

You will discuss with your surgeon (called a pediatric urologist) what the safest and best approach is for your child.

Keep in mind, your child may need to stay in the hospital for one or more nights (depending on the type of surgery) for monitoring.

Ureterostomy Placement

In newborns who cannot yet undergo surgery, a temporary ureterostomy may be placed. This means that the baby's ureter is surgically disconnected from the bladder and brought to the surface of the skin. Urine can then drain into the baby's diaper so that it is not backing up into the kidney.

Ureteral reimplantation can be performed later, usually around 6 to 18 months of age.

A Word From Verywell

If your child has been diagnosed with a UVJ obstruction (perhaps through a prenatal ultrasound), it's expected to feel anxious or overwhelmed. The good news is that surgery can fix the blockage, allowing your child to have normal kidney function.

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