AUA Summit - What is a Ureterocele?


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What is a Ureterocele?

Most of us are born with two ureters, one from each kidney to drain urine into the bladder. Some (1 in 125 people), on the other hand, have two ureters draining a kidney. This is called "duplex anomaly" of the kidney. A "duplex anomaly" can be linked with many conditions that can affect kidney health. One of these conditions is called "ureterocele."

Ureterocele is a congenital anomaly (present at birth) that affects girls more than boys. It is simply a swelling limited to the end of the ureter as it enters the bladder. The swelling resembles a balloon on ultrasound or during a camera examination of the bladder. Ureteroceles in duplex anomalies can be linked with urine refluxing (going) backward to the kidney through the second adjacent ureter. This reflux is related to weakness of the flap valve from having the ureter join the bladder in an abnormal location.

The good news is diagnostic tests and treatments can find and fix this problem.

Here, we give more details about what to do with an ureterocele.

What happens under normal conditions?

Normally, the kidneys filter and remove waste and excess water from the blood to make urine. Urine travels from the kidneys down narrow tubes called ureters. The ureters bring urine to the bladder, where it is then stored. There is a flap valve between the ureters and the bladder to keep urine flowing in only one direction. If urine wrongly flows back to the kidneys, this is a problem called vesicoureteral reflux (VUR).

When the bladder empties, urine flows out of the body through the urethra. This is the tube that starts at the bottom of the bladder. The urethra travels to the end of the penis in boys, or out the front of the vagina in girls.

What is a ureterocele?

An ureterocele happens when the end of ureters that enters the bladder don’t develop properly. It is thought to be a birth defect. The ureteral end swells like a balloon that may stop flow of urine to the bladder.

Ureteroceles can:

  • Swell a lot, taking up most of the bladder, or swell only a small amount.
  • Be inside the bladder (intravesical) or outside the bladder, through the bladder neck and urethra (ectopic or extravesical).
  • Happen with a single ureter or a double ureter (duplex collecting system). In 90% of girls with an ureterocele, the problem is from this.
  • Happen with or without vesicoureteral reflux (VUR) (urine flowing back to the kidneys).
  • Happen on both sides, from both kidneys (bilateral ureterocele).

Ureteroceles are most often found in children age two or younger. Sometimes it is found older children or adults. In some cases it can also be found when a baby is still inside a mother on a prenatal ultrasound.

What are some complications of an ureterocele?

The main problem from ureterocele is kidney damage and kidney infection. Urine blockage may damage the developing kidneys and reduce their ability to filter.

Reflux of urine backward to the kidney is also common, especially when there are two ureters in one kidney. This is because the ureterocele distorts the normal one-way valve between the ureter and bladder. Reflux into the opposite kidney may happen. There is also a small risk for kidney stones. In rare cases, ureterocele in girls can protrude outside the urethra and be visible as a balloon.


Usually there are no symptoms. If there are signs, they can be:


This is a birth defect and cannot be prevented, but it can be treated.


Often, ureteroceles can be seen during maternal ultrasounds before the birth of a child. Still, they may not be diagnosed until a child is seen for another problem, like a urinary tract infection.

Ultrasound is the first imaging test used to find this condition. Other imaging studies may be done to help learn what is going on, and for treatment. For an infant or small child, the below tests may be done:

  • A voiding cystourethrogram (VCUG) may be done to see the bladder in action. This is a series of X-rays of the bladder and lower urinary tract taken with a special dye. First a catheter is placed into the urethra to fill the bladder with a water-based dye. It is removed. Then many X-rays are taken as the patient empties the bladder. These images allow radiologists to find problems in the flow of urine through the body.
  • When a ureterocele has been found, it is also of great value to test the kidneys for damage and evidence for blockage to urine flow across the ureterocele. A nuclear renal scan will show these details. 
  • In cases were the relevant anatomy is not clear, an MRI test may also be done. This will allow the surgeon to better prepare for surgery (if needed).


The timing and type of treatment used are based on a few things:

  • The age and health of the patient
  • Whether or not the kidney is affected
  • Whether or not VUR is present

Sometimes, more than one procedure is needed. Sometimes, observation (no treatment) may be suggested.

The below are treatment options:


Transurethral Puncture

With this treatment, the ureterocele is punctured and decompressed. To do this a cystoscope (a thin tube with camera and light on the end) is used. It usually takes 15 to 30 minutes and can be done without an overnight stay in the hospital. This treatment doesn't use a large cut. But, if the ureterocele wall is thick, it may not work. If it doesn't work, an open operation may be needed. Also, there is a slight risk of causing an obstructive flap valve. This would make it hard to pass urine. This treatment works best when the ureterocele is within the bladder (orthotopic).

Upper Pole Nephrectomy or Uretero-ureterostomy

In some cases, the upper half of the kidney does not function from a ureterocele. If there is no urine reflux in the second ureter, the damaged part of the kidney may be removed. This operation is done either through a small cut under the ribs, or laparoscopically.

Another option is to take the poorly functioning part of the kidney’s ureter and attach it to the second ureter of that kidney. This is called a ureter-ureterostomy and is done through a small cut in the lower abdomen on the side of the ureterocele, laparoscopically or robotically.


If the entire kidney does not work because of the ureterocele, it must be removed. Usually this can be done laparoscopically or robotically. Sometimes a small cut is needed.

Removal of the Ureterocele and Ureteral Reimplantation

If the ureterocele must be removed, then an operation is done. For this surgery, the bladder is opened, the ureterocele is removed, the floor of the bladder and bladder neck are rebuilt and the ureteral flap valve recreated to prevent urine from flowing backward to the kidney. The operation is done with a small cut in the lower abdomen. It is a complex surgery, but it is successful 90-95% of the time.

Ureteropyelostomy or Upper-to-Lower Ureteroureterostomy

If the upper part of the ureter works well, and there is no reflux in the lower part ureter, one option is to connect the obstructed part to the non-obstructed part of the ureter or kidney. The operation is done with a small cut in the lower abdomen. The success rate is 95%.


Antibiotics are used to fight bacteria and prevent kidney infection. A child with a possible urine block or urine reflux may be given a small dose of antibiotics to be taken once a day to prevent infections until the defect is corrected.

Frequently Asked Questions

My baby was diagnosed with an ureterocele on a prenatal ultrasound. She seems very healthy. Is it absolutely necessary for her to undergo treatment?

To prevent kidney damage and UTIs, treatment is often suggested. Sometimes, a “watch and wait” approach is used. It is of great value to continue observing the child to make sure the problem either self-corrects, or is surgically corrected.

My doctor has suggested that my daughter take antibiotics because she has an ureterocele and urinary reflux. Is it safe to take antibiotics every day?

Many children and adults take a low dose of an antibiotic every day to prevent urinary tract infections. This is called a prophylactic antibiotic. This form of therapy has been used for over 35 years. It has proven to be relatively safe, as long as the dose is small. It is of great value to weigh the risk of taking the antibiotic against the risk of a serious kidney infection.

My child was diagnosed with an ureterocele and it was punctured through a small scope. Now there is reflux into the ureterocele and the lower part of the kidney. Will more surgery be needed?

In most cases, if there is reflux up the ureter into the lower part of the kidney, the reflux should be treated. It is unlikely to go away with time. If this is the case, removal of the ureterocele and ureteral re-implantation (recreation of the flap valve) is suggested.

Updated March 2024. 

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