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Megaureter

The vast majority of children are born with urinary tracts that are normal in appearance and function normally efficiently. But in some infants, megaureters, an abnormal widening of the connecting tube between the kidneys and bladder, can cause infections and obstructions, and possibly 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.), a megaureter is a tube that is greater than 10 mm. (three-eighths of an inch) in diameter hence the term "megaureter" ("large ureter"). Certain conditions produce this abnormal widening. The condition of megaureter can result from an abnormality of the ureter itself (primary) or from conditions related to the bladder obstruction (secondary).

What are the different types of megaureters?

Most megaureters are classified as the following:

  • primary obstructed megaureter: A distinct anatomical blockage where the ureter enters the bladder. This obstruction of the ureter then causes the abnormal widening of the ureter. The obstruction can produce damage to the kidney over time. This condition, when accurately diagnosed, is likely to require surgical repair for its correction and relief of obstruction. Even though the problem may improve with time, diligent follow up is necessary.
  • refluxing megaureters: These ureters are wide because of abnormal backward flow of urine (vesicoureteral reflux) up the ureters from the bladder. Normally, once that urine is in the bladder, it should not go back up the ureters. Refluxing megaureters are an extreme presentation of vesicoureteral reflux, and can be seen more commonly in newborn males. In some of these patients, the degree of reflux, and widening of the ureters, can improve over the first year of life. Persistently refluxing megaureters require surgical correction by a procedure termed ureteral reimplantation, and by possibly tapering or surgically narrowing the caliber of the ureters. The condition of refluxing megaureters may be linked to the condition known as "megacystis megaureter syndrome," 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. Accurate evaluation of these wide ureters is necessary to exclude both obstruction and reflux as the causes of the widening.
  • obstructed, refluxing megaureters: An obstructed ureter that also suffers from reflux. A dangerous combination since the ureters gets 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, but evaluation is necessary to assure that there is no potential compromise of kidney function which may later produce symptoms.

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 widened 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 program, 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.

Magnetic resonance of the urinary tract (MR-U): this evolving technology produces excellent imaging of the urinary tract, much more accurately than IVP’s, and may become the most anatomically sensitive imaging study of the urinary tract for conditions such as megaureters It also involves injecting dye and imaging the urinary tract using magnetic resonance technology. Its use in small children is limited because of the need for sedation or possibly general anesthesia.

How is a megaureter treated?

If tests reveal an obstruction or impaired kidney function, your child may need surgery to correct the problem. The typical operation for megaureters is called ureteral reimplantation and ureteral tapering, the technical term urologists use for inserting the ureters back into the bladder and 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.

Currently, most symptomatic megaureters are best treated by this open type of surgery where the blockage is removed (for obstructed megaureters), the efflux is corrected (for refluxing megaureters) and possibly the ureters are trimmed (for very wide ureters). Minimally invasive technologies such as injection of substances to correct reflux or laparoscopy for ureteral reimplantation are not currently applicable for megaureters.

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 persistent or new vesicoureteral reflux. Obstruction may occur soon after the operation or after a longer period of time. Fortunately, this complication occurs in only 5 percent of cases and it may require additional surgery. 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. A renal scan is often done to assure that function is preserved or improved, and that obstruction is corrected, and a VCUG is often obtained a few months after surgery to assure that reflux is not present.

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.

Links for additional information:

American Academy of Pediatrics, Section on Urology



Reviewed: January 2011

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Megaureter Glossary
  • abdomen: Also referred to as the belly. It is the part of the body that contains all of the internal structures between the chest and the pelvis.

  • abnormality: A variation from a normal structure or function of the body.

  • anatomy: The physical structure of an internal structure of an organism or any of its parts.

  • anesthesia: Loss of sensation in any part of the body induced by a numbing or paralyzing agent. Often used during surgery to put a person to sleep.

  • antibiotic: Drug that kills bacteria or prevents them from multiplying.

  • antibiotic prophylaxis: Daily treatment with antibiotics to prevent infection.

  • bladder: The bladder is a thick muscular balloon-shaped pouch in which urine is stored before being discharged through the urethra.

  • catheter: A thin tube that is inserted through the urethra into the bladder to allow urine to drain or for performance of a procedure or test, such as insertion of a substance during a bladder X-ray.

  • cyst: An abnormal sac containing gas, fluid or a semisolid material. Cysts may form in kidneys or other parts of the body.

  • cystourethrogram: Also called a voiding cystogram. A specific X-ray that examines the urinary tract. A catheter (hollows tube) is placed in the urethra (tube that drains urine from the bladder to the outside of the body)and the bladder is filled with a liquid dye. X-ray images are taken as the bladder fills and empties. The X-rays will show if there is any reverse flow of urine into the ureters and kidneys.

  • dilatation: Process of widening or being widened.

  • dilate: Widen.

  • dilated: Widened.

  • diuretic: A drug that increases the amount of water in the urine, removing excess water from the body.

  • excretory: unwanted or undigestable matter.

  • extravesical: Outside the bladder.

  • fetal: Relating to or characteristic of a fetus (unborn offspring after eight weeks of development).

  • fetus: An unborn offspring from the end of the eighth week of conception until birth.

  • gene: The basic unit capable of transmitting characteristics from one generation to the next.

  • general anesthesia: Person is put to sleep with muscle relaxation and no pain sensation over the entire body.

  • genetic: Relating to the origin of something.

  • hydronephrosis: Swelling at the top of the ureter usually because something is blocking the urine from flowing into or out of the bladder.

  • hydronephrosis: Swelling of the top of the ureter, usually because something is blocking the urine from flowing into or out of the bladder.

  • hydronephrosis: Swelling at the top of the ureter, usually because something is blocking the urine from flowing into or out of the bladder.

  • incision: Surgical cut for entering the body to perform an operation.

  • infection: A condition resulting from the presence of bacteria or other microorganisms.

  • intravenous: Also referred to as IV. Existing or occurring inside a vein.

  • intravenous pyelogram: Also referred to as IVP, intravenous urography or excretory urogram. An X-ray of the urinary tract. A dye is injected to make urine visible on the X-ray and show any blockage in the urinary tract.

  • invasive: Not just on the surface; with regard to bladder cancer, a tumor that has grown into the bladder wall.

  • invasive: Having or showing a tendency to spread from the point of origin to adjacent tissue, as some cancers do. Involving cutting or puncturing the skin or inserting instruments into the body.

  • ions: Electrically charged atoms.

  • IV: Also referred to as intravenous. Existing or occurring inside a vein.

  • IVP: Also referred to as intravenous pyelogram, intravenous urography or excretory urogram. An X-ray of the urinary tract. A dye is injected to make urine visible on the X-ray and show any blockage in the urinary tract.

  • kidney: One of two bean-shaped organs that filter wastes from the blood and discharge these waste products in urine. The kidneys are located on either side at the level of the 12th ribs toward the back. The kidneys send urine to the bladder through tubes called ureters.

  • kidneys: One of two bean-shaped organs that filter wastes from the blood and discharge these waste products in urine. The kidneys are located on either side at the level of the 12th ribs toward the back. The kidneys send urine to the bladder through tubes called ureters.

  • laparoscopy: Surgery using an instrument in the shape of a tube that is inserted through the abdominal wall to give an examining doctor a view of the internal organs.

  • megacystis megaureter: An extreme form of the primary refluxing megaureters, in which massive reflux prevents effective bladder emptying.

  • megaureter: Wide ureter.

  • neonatal: Newborn baby.

  • neurogenic: Causing or relating to the disorder of nerves.

  • neurogenic bladder: Also called neuropathic bladder. Loss of bladder control caused by damage to the nerves controlling the bladder.

  • obstruction: something that obstructs, blocks, or closes up with an obstacle

  • posterior: Situated at the rear or behind something.

  • posterior urethral valves: Congenital obstruction of the urinary tract in boys produced by lips of tissue or valves in the area of the prostatic urethra.

  • prenatal: Before birth.

  • prenatal fetal sonography: Sonogram taken of the fetus during pregnancy.

  • prenatal hydronephrosis: Swelling of the kidney before birth.

  • prenatally: Before birth.

  • prune belly syndrome: A triad of congenital symptoms that include multiple tract abnormalities. The common abnormalities include the absence of abdominal muscles, undescended testicles and abnormalities of the upper urinary tract.

  • radioactive: Relating to or making use of radioactive substances or the radiation they emit.

  • reflux: Backward flow of urine. Also referred to as vesicoureteral reflux (VUR). An abnormal condition in which urine backs up from the bladder into the ureters and occasionally into the kidneys, raising the risk of infection.

  • reflux: Backward flow.

  • renal: Pertaining to the kidneys.

  • renal scan: A nuclear medicine examination that uses small amounts of radioactive materials to measure the function of the kidneys.

  • sedation: State of calm relaxation induced in one or more body systems by administration of medical agents (sedatives).

  • stent: With regard to treating ureteral stones, a tube inserted through the urethra and bladder and into the ureter. Stents are used to aid treatment in various ways, such as preventing stone fragments from blocking the flow of urine.

  • stone: Small hard mass of mineral material formed in an organ.

  • symptomatic: Having to do with a symptom or symptoms that arise from and accompany a particular disease or disorder and serves as an indication of it.

  • transvesical: Through the bladder.

  • ultrasound: Also referred to as a sonogram. A technique that bounces painless sound waves off organs to create an image of their structure to detect abnormalities.

  • urate: A salt of uric acid.

  • ureter: One of two tubes that carry urine from the kidneys to the bladder.

  • ureteral: Pertaining to the ureter. Also referred to as ureteric.

  • ureteral reimplantation: Surgery to create a new, longer tunnel for the ureter to pass through the bladder wall.

  • ureteral stones: A kidney stone that has moved down into the ureter.

  • ureters: Pair of tubes that carry urine from each kidney to the bladder.

  • ureters: Tubes that carry urine from the kidneys to the bladder.

  • urethra: A tube that carries urine from the bladder to the outside of the body. In males, the urethra serves as the channel through which semen is ejaculated and it extends from the bladder to the tip of the penis. In females, the urethra is much shorter than in males.

  • urethral: Relating to the urethra, the tube tha carries urine from the bladder to outside the body.

  • urge: Strong desire to urinate.

  • urinary: Relating to urine.

  • urinary tract: The system that takes wastes from the blood and carries them out of the body in the form of urine. Passageway from the kidneys to the ureters, bladder and urethra.

  • urinary tract infection: Also referred to as UTI. An illness caused by harmful bacteria, viruses or yeast growing in the urinary tract.

  • urine: Liquid waste product filtered from the blood by the kidneys, stored in the bladder and expelled from the body through the urethra by the act of urinating (voiding). About 96 percent of which is water and the rest waste products.

  • urologist: A doctor who specializes in diseases of the male and female urinary systems and the male reproductive system. Click here to learn more about urologists. (Download the free Acrobat reader.)

  • urology: Branch of medicine concerned with the urinary tract in males and females and with the genital tract and reproductive system of males.

  • vas: Also referred to as vas deferens. The cordlike structure that carries sperm from the testicle to the urethra.

  • VCUG: Also referred to as voiding cystourethrogram or voiding cystogram. A catheter is placed in the urethra and the bladder is filled with a contrast dye. X-ray images are taken as the bladder fills and empties to show any blockage or reverse urine flow.

  • vein: Blood vessel that drains blood away from an organ or tissue.

  • vesicoureteral reflux: Also referred to as VUR. An abnormal condition in which urine backs up from the bladder into the ureters and occasionally into the kidneys, raising the risk of infection.

  • void: To urinate, empty the bladder.

  • voiding: Urinating.

  • voiding cystourethrogram: Also referred to as VCUG or voiding cystogram. A specific X-ray that examines the urinary tract. A catheter (hollows tube) is placed in the urethra (tube that drains urine from the bladder to the outside of the body)and the bladder is filled with a liquid dye. X-ray images are taken as the bladder fills and empties. The X-rays will show if there is any reverse flow of urine into the ureters and kidneys.

Megaureter Anatomical Drawings

click images for a larger view
 

 

 

 

 

 

 

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