Gerald R. Jerkins MD
UT Le Bonheur Pediatric Specialists
Memphis Tennessee


On this page:
What are Megaureters
Symptoms of Megaureters
How is a Megaureter treated?
What can be expected after treatment for a megaureter?
Frequently Asked Questions


The vast majority of children are born with urinary tracts that function efficiently. But in some infants, megaureters, a widening or swelling of the connecting tube between the kidneys and bladder, can cause infections, obstructions and even serious kidney damage if the problem is not diagnosed and treated. But what are the symptoms? The information below should give you a head start about this potentially serious health hazard.

What are megaureters?

The ureters are tube-like structures in the body that carry or propel urine from the kidneys to the bladder. While the normal width of a child's ureter is three to five millimeters (mm.), megaureters are greater than 10 mm. (three-eighths of an inch) in diameter hence the term "megaureter". Certain conditions produce this abnormal widening. It can result from an abnormality of the ureter itself or for a secondary reason.

What are the different types of megaureters?

Most megaureters are classified as the following:

  • primary obstructed megaureter: A distinct blockage where the ureter enters the bladder. The obstruction can produce damage to the kidney over time. Even though the problem may improve with time, diligent follow up is necessary.
  • refluxing megaureters: Source of a backward flow of urine (vesicoureteral reflux). It is linked to megacystis megaureter, a condition where the bladder, instead of emptying completely, is enlarged due to cycling of urine between it and the ureters via reflux.
  • non-obstructive, non-refluxing megaureters: These are wide ureters not caused by obstruction or urine backflow. Many of these improve with time.
  • obstructed, refluxing megaureters: An obstructed ureter that also suffers from reflux. A dangerous combination since the ureters get bigger and more blocked with time.
  • secondary megaureters: These enlarged ureters appear in association with other conditions such as posterior urethral valves, prune belly syndrome and neurogenic bladder.

What are the symptoms of megaureter?

In the past, the majority of megaureters were found during the evaluation of a child with a urinary tract infection. These patients usually experience fever, back pain and vomiting.

But today, because of the widespread use of prenatal fetal sonography, more megaureters are discovered as prenatal hydronephrosis or dilatation of the urinary tract in the fetus.

Because megaureters can cause a severe infection or obstruction that leads to kidney damage, this health issue is potentially serious. Dilatation of the urinary tract may imply a blockage or obstruction, but that is not always the case. In some situations, a dilated ureter may not affect the kidney at all. Also, most patients with prenatally detected megaureters do not experience symptoms related to this wide ureter.

How is a megaureter diagnosed?

If your child develops a urinary tract infection, or other symptoms that could signal this condition, check with your doctor. Further investigation is warranted. You can expect the urologist to conduct a series of tests to clarify the anatomy and function of the urinary tract. They include:

ultrasound: Also known as sonography, this simple and painless imaging test is usually done to evaluate the appearance of the kidney, ureter and bladder. The study is highly sensitive in detecting troubled ureters. In fact, while sonography rarely picks up normal ureters because of their narrowed size, this technology produces excellent images of dilated ones.

voiding cystourethrogram (VCUG): A VCUG is done to determine if vesicoureteral reflux is occurring. A small catheter is inserted through the urethra into the bladder and a contrast dye is injected into the bladder before X-rays are taken. If reflux is present, the image will show the contrast produced by the backflow into the ureter.

diuretic renal scans: Used to evaluate for a possible obstruction, this test is performed by injecting a radioactive substance into a vein, which is then carried to the kidneys. While the study yields data about a possible blockage, it also gives physicians information about the organ's function.

intravenous pyelogram (IVP): Also referred to as excretory urogram, IVP is performed by injecting dye into a vein and taking X-ray pictures of the abdomen as the dye is emptied from the kidneys. While renal scans have replaced IVP in evaluating dilated urinary tracts, this test can be extremely helpful in questionable cases.

How is a megaureter treated?

If tests reveal an obstruction or impaired function, your child may need surgery to correct the problem. The typical operation for megaureters is called ureteral reimplantation, the technical term urologists use for trimming the widened ureter. Unless the child has a urinary tract infection or decrease in kidney function, the surgery can be delayed until 12 months of age. Surgery in infants is technically demanding and such should be performed by individuals experienced with neonatal surgery. Many babies are kept on antibiotic prophylaxis during this period of observation to minimize the likelihood of infections.

During the procedure, the surgeon makes an incision in the lower abdomen and, depending on the child's anatomy, approaches the ureter through either the bladder (transvesical) or from outside the bladder (extravesical). The ureter is disconnected from the bladder, and if very wide, it may need to be trimmed (tapered) and then replaced in the bladder. If an obstruction exists, it is removed. Your child may have a catheter for a few days to improve healing. Hospitalization is usually between two and four days.

What can be expected after treatment for a megaureter?

Several weeks after surgery, some of the tests that were done before surgery may need to be repeated to determine the success of the surgery. The size of the ureter may not improve immediately after surgery, so evaluation over time will be necessary to ensure a good outcome. Potential complications of surgery are bleeding, obstruction of the ureter and vesicoureteral reflux. Obstruction may occur soon after the operation or after a long period of time. Fortunately, this complication occurs in only 5 percent of cases and it may require additional surgery. A vesicoureteral reflux complication may occur after surgery in 5 percent of the cases and may improve with time. Most patients are followed for a number of years, using ultrasound, to ensure that the appearance of the kidney and ureter continues to improve.

Frequently asked questions:

Is this condition genetic?

At this time scientists do not know if there are genetic links.

Is surgery always necessary to correct a megaureter?

No. Some megaureters may improve over time without the need for surgery. However, it is important to prevent infections during the time of observation so antibiotics are usually prescribed.

Is minimally-invasive surgery an option?

It may be possible to place a stent or catheter through the blocked portion of the megaureter as a temporary procedure to improve the drainage of the kidney. Laparoscopic techniques are not presently well developed to correct most megaureters but that may change in the future.

Are there long-term problems if we do not do anything?

Possibly yes. They include ureteral stones, urinary tract infection, deterioration of kidney function and back pain.