Urology: Ectopic Ureter
What is an ectopic ureter?
Most of children are born with two ureters, one to drain the urine from each kidney into the bladder. But nature has given some children more than the normal allotment. In most cases, a bonus ureter causes no problems. Yet what if one of these ureters it is not connected correctly — and drains incorrectly? That is the case for children with an ectopic ureter, a bonus that is not a plus. Luckily, medicine has given urologists a bevy of diagnostic tests and surgical techniques to deal with this abnormality.
What are the causes of ectopic ureter?
Normally, there is a single ureter draining the urine from each kidney to the bladder. The urine is then stored in the bladder until one voluntarily urinates. Occasionally, there may be two ureters draining a single kidney. One ureter drains the upper part of the kidney and the second ureter drains the lower portion. So long as they both enter the bladder normally, this "duplicated collecting system" is not a problem. Rarely a child may be born with an ectopic ureter. This is a ureter which fails to connect properly to the bladder and drains somewhere outside the bladder. In girls, the ectopic ureter usually drains into the urethra or even the vagina. In boys, it usually drains into the urethra near the prostate or into the genital duct system. An ectopic ureter can occur in a non-duplicated collecting system but is more common in a duplicated system.
What are the symptoms of ectopic ureter?
Blockage of the ureter or the inability to control urination can indicate an ectopic ureter. Poor drainage, accompanied by back pressure, can cause the ureter and portion of the kidney it services to become distended or swollen. This condition is called hydronephrosis and can be spotted easily on an ultrasound. For this reason, many babies with an ectopic ureter are detected when the pregnant mother undergoes a prenatal ultrasound. However, not all ectopic ureters are hydronephrotic so they may not be detected by an ultrasound.
Poor drainage from an ectopic ureter may make children more likely to have urinary tract infections. In addition to hydronephrosis, ectopic ureters in girls may cause incontinence since the ureter drains urine directly into or near the vagina. This problem becomes evident after toilet-training. It is usually distinguished from other forms of incontinence in girls because the incontinence is a constant dripping moistness rather than episodes of loss of bladder control. Some girls will be treated with medication and other therapies for many years before the correct diagnosis of an ectopic ureter is made. Boys with ectopic ureters do not generally have incontinence since the ectopic ureter drains inside the body. However, they may still show symptoms of hydronephrosis or a urinary tract infection.
When an ectopic ureter is present, there may also be a slight flaw in the normal ureter's connection between the kidney and bladder. This flaw can result in vesicoureteral reflux, a disruption of the passage of urine from the kidney, through the ureter, to the bladder and finally out the urethra. With reflux, as the bladder fills or empties some urine flows backward into the kidney. Vesicoureteral reflux places patients at a higher risk for kidney infections and is another reason some children with ectopic ureters show signs of a urinary tract infection.
How is ectopic ureter diagnosed?
The evaluation of an ectopic ureter depends on the problem shown by the child. For instance, if hydronephrosis is detected on a prenatal ultrasound, then the ultrasound is usually repeated after the child is born. A bladder X-ray, called a voiding cystourethrogram (VCUG) is then taken to rule out vesicoureteral reflux as the cause for swelling of the kidney and ureter. The VCUG is also used to determine if there is reflux in a second ureter associated with the ectopic ureter. Usually with the combination of an ultrasound and a VCUG, the doctor can determine if there is hydronephrosis. Sometimes other diagnostic studies such as renal flow scan or a formal kidney X-ray, called an intravenous pyelogram (IVP), may help to clarify the anatomy. The kidney or portion of the kidney drained by the ectopic ureter often functions poorly. This can be assessed with a renal flow scan. Both tests involve an injection of contrast dye picked up by the kidney and then seen either by standard X-ray pictures (for an IVP) or with a special camera for detecting small amounts of radioactivity in the dye (for the renal flow scan). This functional information may be important in selecting the form of treatment. Finally, a cystoscopy may be performed (often at the time of definitive treatment). In this test, usually performed under general anesthesia, a small telescope is placed into the urethra and vagina and the openings of the ureters from both kidneys are identified. Unfortunately, the ectopic ureter's opening cannot always be identified. However, by identifying the number and location of the other ureter openings, the diagnosis can usually be confirmed.
When a child shows symptoms of urinary incontinence, the same sequence of tests is usually undertaken, however, if the ureter is not swollen and there is no associated reflux, the ultrasound and VCUG may be normal. If the symptoms suggest an ectopic ureter, then sometimes this can be seen on a renal flow scan or IVP. Occasionally, a CT scan is needed to see the ectopic ureter and the portion of the kidney it drains. The diagnosis is not always easy to make and since other causes of incontinence are very common in children, some children may be incontinent for years before the diagnosis is made.
Treatment for an ectopic ureter:
The treatment for ectopic ureter is surgery. To control the risk of infection, the patient may be placed on a low dose of antibiotics prior to surgery.
While there are three surgical techniques — nephrectomy, ureteropyelostomy and ureteral reimplantation — to correct this problem, each has advantages and disadvantages.
Nephrectomy (upper pole heminephrectomy): In this surgery, the kidney or the portion of it that is drained by the ectopic ureter is removed. This stops the flow of urine into the ectopic ureter, thus curing the incontinence and reducing the chance of infection. Technically the simplest operation, it also has the lowest complication risk. It is particularly attractive when the kidney or portion of the kidney draining through the ectopic ureter is functioning poorly. It may also be used when that kidney portion is functioning properly if the opposite kidney is normal. This operation has been traditionally performed through an incision under the ribs but can now be done laparoscopically in some patients. The main disadvantages are that the potentially functioning kidney tissue may be removed and the bottom end of the ectopic ureter is left in place. While usually not a problem, the remaining part of the ectopic ureter can be a future source for infection.
Ureteropyelostomy: In this procedure, the ectopic ureter is divided near the kidney and sewn into the normal collecting system of the lower part of the kidney. This allows the urine from the upper part of the kidney to drain normally. It has the advantage of protecting all the kidney tissue but still leaves the bottom half of the ectopic ureter in place. It also has a slightly higher complication rate than the other operations.
Ureteral reimplantation: In this operation, the ectopic ureter is divided near the bottom and sewn into the bladder in such a way that urine drains well and does not flow backwards. Usually performed through an incision above the pubic bone, this procedure has a slightly higher complication rate than the other two surgeries. It can also be technically difficult if performed in small infants. However, like ureteropyelostomy, this operation preserves all kidney tissue. Furthermore, it removes more of the abnormal ectopic ureter than the other two procedures and allows the surgeon to stop any vesicoureteral reflux.
