What is a Ureterocele?

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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 associated with a variety of conditions that can affect the kidney health. One of these conditions is referred to as "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 associated with urine refluxing 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.

Luckily, diagnostic tests and treatments can find and repair this problem.

Here, we provide more information about what to do with an ureterocele.

What happens under normal conditions?

Male Urinary Tract
Male Urinary Tract
Medical Illustration Copyright © 2015 Nucleus Medical Media, All rights reserved

Female Urinary Tract
Female Urinary Tract
Medical Illustration Copyright © 2015 Nucleus Medical Media, All rights reserved

Normally, the kidneys filter and remove waste and excess water from the blood to produce 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 considered 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 2 or younger. Sometimes it is found older children or adults.

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.