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What is megaureter?

Megaureter is the medical term for an enlarged ureter. The ureter is a tube-like structure that urine passes through on its way from the kidney to the bladder. Each person has two ureters, one for each kidney. Together, the ureter and the kidney collecting system are referred to as the upper urinary tract.

Boys are more likely than girls to have a megaureter. The condition often has no symptoms and, in infants it may clear up on its own. In older children, megaureter can cause urinary tract infections (UTIs). In some cases it can cause kidney damage.

How we care for megaureter

The Department of Urology at Boston Children's Hospital has been caring for children for over 30 years. Our physicians are dedicated to pediatric urologic care, surgical expertise, and research in all aspects of pediatric urology. We perform more than 3,000 surgical procedures and care for 20,000 children worldwide each year. Further, our highly trained nurses, nurse practitioners, physician assistants, psychologists, social workers, and child life specialists are available to help your child through each and every test and procedure.

Megaureter | Symptoms & Causes

What are the symptoms of megaureter?

There's a good chance that your child will not show any symptoms of megaureter. Often, the condition is detected on prenatal ultrasound. However, some children experience one or more of the following symptoms during infancy or early childhood:

  • abdominal mass that can be seen or felt
  • pain in the back or abdomen
  • urinary tract infection with fever
  • hematuria (blood in the urine)
  • urinary incontinence
  • urolithiasis (stone formation within the urinary tract)

What causes megaureter?

There can be different causes for megaureter.

Normally the ureter is made up of flexible, muscular tissue. Some children are born with stiff, inflexible tissue at the bottom of one or both of their ureters, however. Without flexible tissue at this location, movement of urine to the bladder is more difficult. Instead, urine backs up inside the ureter and causes it to stretch.

In other children megaureter is caused by a trouble with urination. Some of the urine that is supposed to flow out of the kidney into the bladder travels backward up the ureter toward the kidney. This is called vesicoureteral reflux and is often more severe in grade.

Megaureter | Diagnosis & Treatments

How is megaureter diagnosed?

If your child has been referred to a specialist who suspects megaureter, there will be a complete evaluation of the urinary tract. The initial evaluation typically includes an ultrasound of the kidneys, ureters, and bladder.

Other studies are usually needed to confirm the diagnosis and determine the cause. These may include:

  • Voiding cystourethrogram (VCUG) is a specialized x-ray. It is used to determine whether vesicoureteral reflux (backward flow of urine from the bladder to the ureter and/or kidney) may be causing the problem.
  • A kidney scan is used to evaluate the degree of obstruction at the junction where the ureter meets the bladder. This scan also provides very detailed information about kidney function.

Once the doctor has checked for vesicoureteral reflux and obstruction, she will assign your child's megaureter or dilated upper urinary tract into one of the four following categories:

  • refluxing megaureter: vesicoureteral reflux alone is responsible for the megaureter
  • obstructed megaureter: significant blockage at the ureterovesical junction (UVJ) alone is responsible
  • refluxing and obstructed megaureter: both vesicoureteral reflux and blockage at the UVJ are present
  • nonrefluxing and nonobstructed megaureter: the upper urinary tract is dilated (wider than normal), but there is no evidence of vesicoureteral reflux or clinically significant obstruction

Even after the cause of your child's megaureter is determined, the doctor may want to perform additional tests to get a more complete picture of kidney and bladder function. These tests may include:

  • specialized renal scans and/or laboratory tests of your child’s blood and urine
  • blood testing to evaluate how well the kidney functions to filter blood
  • urodynamic evaluation to measure how well the bladder stores and empties urine
  • MRI (magnetic resonance imaging) to evaluate the detailed anatomy of the kidneys, ureters, and bladder in relation to surrounding structures

How is megaureter treated?

Treatment depends on the cause of the megaureter. In some cases, the condition clears up on its own. If this is the case, it is important to follow the doctor’s advice and bring your child in for follow-up visits as recommended.

If your child’s ureter is blocked, they may need surgery to remove the blockage. It is often possible to delay surgery until a child is at least 12 months old.

If your child has reflux (urine traveling backwards up the ureter), they may be given a once-a-day antibiotic. This will help prevent a urinary tract infection (UTI).

Megaureter | Programs & Services