Dilation of the Kidney in Children

What is hydronephrosis?
Hydronephrosis is dilation (enlargement) of the urinary drainage system that transmits urine from the kidney to the bladder. It is not uncommon to see dilatation of the kidney drainage system of a fetus before birth, which may be discovered when a pregnant woman has an ultrasound. When we test these children after birth, we may find one of the following:

• the dilation is gone
• the urinary drainage system is blocked (obstructed)
• urine is backing up into the kidney(s) from the bladder (a problem called reflux)
• the urinary drainage system remains enlarged but there is no obstruction or reflux

In older children, hydronephrosis may be discovered when the child has pain in the side, vomiting, urinary tract infection or high blood pressure.

What is the significance of kidney obstruction?
Whether obstruction causes damage to kidney function depends on the degree of blockage and the age of the patient.

What tests are needed to identify the severity of the problem?

The first test, which usually identifies the problem, is a kidney (renal) ultrasound. We may recommend two other tests: a bladder x-ray (VCUG) to rule out reflux and a renal scan to measure kidney function.

VCUG
In this test, a small catheter (tube) is passed into the bladder. The bladder is filled with x-ray liquid and pictures are taken in order to evaluate the bladder and urethra. It also will demonstrate Reflux (urine going backward from the bladder to the Kidney).

Renal scan
A small amount of a tracer substance is injected into a vein. Pictures are taken with a camera for an hour or longer. Early in the test, a drug that stimulates urine production (Lasix) is given to wash urine out of the kidneys. This test tells us how well each kidney works as compared to the other kidney and how fast each kidney drains. Kidneys that do not drain well may be obstructed, and the point of blockage can be seen on the scan.

What causes obstruction?
The most common kind of obstruction is blockage of the urinary drainage system at the beginning of the ureter, or the tube that connects the kidney and bladder. This is called ureteropelvic junction obstruction.

The ureter may also be blocked at its connection with the bladder, called ureterovesical junction obstruction.

How is obstruction treated?
If obstruction is mild or partial, we may suggest that it be observed for a while. In other cases, surgery is recommended. If we decide to wait and observe your child, we will recommend repeating the ultrasound and the kidney scan at periodic intervals. If your child should become ill, especially with fever, prior to your next visit, you should have his/her urine checked for infection.

Surgery
Pyeloplasty is the procedure to repair the blockage caused by a Ureteropelvic junction obstruction (UPJ). The UPJ is the point where the urine from the kidney starts to empty into the tube (the ureter) that will carry the urine to the bladder.

Open Pyeloplasty
We perform this procedure through a small incision in the affected side. The operation requires general anesthesia. The repair is done by removing the blocked section and sewing the drainage system back together. We will leave a soft drainage tube coming out of the skin. We may also leave a catheter in the bladder or the kidney. These tubes may all be removed before your child leaves the hospital or left in place until he/she returns to the office. Once they are removed, your child can bathe or shower. All of the stitches dissolve on their own.

Laparoscopic (Robotic) Pyeloplasty
Laparoscopic pyeloplasty allows the surgeon to perform the procedure through three or four very small incisions. We use specialized laparoscopic instruments through these small incisions to remove the blocked section and sew the drainage system back together. We use the DaVinci robot to perform this procedure to allow the surgeon greater dexterity and vision to perform the procedure in a shorter time. We will leave a soft drainage tube coming out of the skin. We may also leave a catheter in the bladder or the kidney. These tubes may all be removed before your child leaves the hospital or left in place until he/she returns to the office. Once they are removed, your child can bathe or shower. All of the stitches dissolve on their own.

We have performed numerous laparoscopic/robotic pyeloplasties with success rates that rival the open surgical technique. Children older than 10 years of age may benefit from the laparoscopic/robotic approach to minimize the size of the incision.

Ureterovesical junction obstruction
An incision is made in the lower abdomen. The area of blockage is removed and the ureter is sewn into the bladder (ureteral reimplantation). Sometimes it is necessary to taper (narrow) the ureter. Afterwards, a tube is left in the bladder and sometimes a ureteral stent and a kidney drainage tube are also left. These tubes will be removed in the hospital or office.

How do I care for my child after surgery?
After any of these procedures, your child will remain in the hospital for 1-2 days. A normal diet will gradually be resumed. He/she will be given pain medication and antibiotics. No stitches will be removed from the incision since they all dissolve. We will encourage you child to take deep breaths and get out of bed as soon as possible after surgery.

What problems can occur after surgery?
As with any surgery, bleeding or infection can occur, but are rare. When blockage is repaired, the area that is fixed can swell and remain blocked for a time. If a drainage tube is already in place, it will remain there until the blockage is gone. Occasionally, it is necessary to put a drainage tube into the kidney temporarily. If blockage persists or recurs, however, another operation may be required. This complication occurs infrequently (less than 10% of the time). When the ureter is sewn into the bladder (reimplant), the obstruction may be cured but reflux (backflow of urine from the bladder to the kidney) may start. If this problem persists for a year or longer, surgical repair may be required.

What happens after surgery?
If a drainage tube was left in place at the time of surgery, your doctor may do an x-ray to make sure everything has healed before it is removed. If no tube was left, we will often do an ultrasound 1-2 months after surgery. A renal scan may be required to make sure that the obstruction is gone. The number of tests done after surgery varies from person to person. However, we recommend kidney ultrasounds for at least 5 years after surgery to make sure that the kidney dilation is better.