Ureteropelvic junction (UPJ) obstruction - Children's Hospital Boston

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Ureteropelvic junction (UPJ) obstruction

Programs that treat this condition

Robotic Surgery

Kidney Transplant Program

What is ureteropelvic junction (UPJ) obstruction?

UPJ obstruction occurs when there is an abnormal narrowing of the ureter at the level where the kidney pelvis and the ureter meet (See Urinary Tract, Normal Anatomy). This abnormal narrowing impedes the flow of urine down the ureter and into the bladder, causing the urine to build up, resulting in a condition known as hydronephrosis, an expansion and dilation of the renal pelvis.

The degree of obstruction at the ureteropelvic junction varies widely, ranging from very mild to very severe. In general, mild cases of UPJ obstruction do not injure or impair the kidney from performing its normal function. Mild UPJ obstruction may, however, predispose a child to increased risk of urinary tract infection. In severe cases of UPJ obstruction, there can be significant impairment or renal damage.

What causes UPJ obstruction?

There are two types of causes of UPJ obstruction, intrinsic causes and extrinsic causes. The intrinsic cause, which is the most common type occurs during fetal development, resulting in a narrowing of the ureter as it's forming, leading to the blockage of urine flow. Extrinsic causes can include an abnormal tethering of the ureter by abnormal blood vessels or compression of the ureter by a tumor.

What are the symptoms of UPJ obstruction?

Most cases of UPJ obstruction are now diagnosed prenatally, due to the common practice of prenatal ultrasound. If the condition is not detected before birth, a child may have the following symptoms: hematuria (blood in the urine), urinary tract infection, abdominal masses or abdominal discomfort.

How is ureteropelvic junction obstruction diagnosed?

In many cases, the condition is diagnosed by prenatal ultrasound. The fetal kidney and collecting system are often detectable on prenatal ultrasound as early as 15 weeks of gestation. The first sign of a problem on the ultrasound is usually hydronephrosis, which is an indication that there may be a blockage of urine flow. You may undergo further ultrasounds during pregnancy, and your baby will be evaluated after birth.

You would also be referred to a pediatric surgeon if your child displays any of the symptoms described above. If the specialist suspects UPJ obstruction, your child will undergo the following tests:

Renal-bladder ultrasound: This is generally the first test performed. The ultrasonographer will be looking to see if the renal pelvis is dilated and if there is any damage to kidney function. The doctor will be able to determine whether the condition is mild, moderate, or severe.
Voiding cystourethrogram:This test is used to determine whether there is vesicoureteral reflux or obstruction below the bladder.
Intravenous Pyelogram (IVP) or Renal Scan: Either of these tests may be performed based on the surgeon's preference. Both tests help to evaluate the severity of obstruction of urine flow from the kidney to the bladder.

Based on the findings of the tests described above, a determination will be made as to whether the condition represents a severe or mild degree of UPJ obstruction, whether it can be safely watched to see if it resolves spontaneously or whether it would be treated best with surgical correction.

How is ureteropelvic junction obstruction treated?

UPJ obstruction can occur in varying degrees of severity. In its very mildest nature, it is most often left alone, with routine observation, since it can correct itself over time. In severe cases of UPJ obstruction, there may be concern about impairment of kidney function or permanent kidney damage and therefore these cases are treated surgically.

The operation usually involves removing the narrow part of the ureter and re-connecting it to the kidneys drainage system, a procedure known as pyeloplasty. This is sometimes done laparoscopically. See Pyeloplasty (laparoscopic).

Laparoscopic Pyeloplasty

When the kidney is obstructed, it may be necessary to perform an operation to correct the obstruction by removing the narrow part of the tube and re-connect the kidneys drainage system. The obstruction is usually near the kidney at what is called the ureteropelvic junction. The operation to correct this problem is called a pyeloplasty and may also be performed laparoscopically using robotic surgery equipment. The open surgery is usually performed through a cut in the side, just under the ribs, or in the back under the rib. Children usually stay in hospital for 3 days.

When a pyeloplasty is performed laparoscopically, it may take a longer time, but children usually can go home within 24 to 48 hours from surgery. The surgery is performed through three or four instrument ports and accomplishes the same thing as open surgery, which is to remove the segment of the ureter causing the obstruction and re-attach the ureter and kidney to permit more normal urine drainage. A tube called a stent may be left in place temporarily to help with healing. The stent needs to be removed with a brief cystoscopy (passing a small telescope into the bladder through the urethra) under a short general anesthesia.

Robotic-assisted laparoscopic surgery may take a longer time, but children usually can go home 24 to 48 hours after surgery.

The specific treatment for UPJ obstruction will be determined in consultation with your physician based on your child's age and overall health, the extent of the condition, your child's tolerance for specific medications, procedures or therapies, expectations for the natural history of the condition, and your opinions and preference.



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