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Ureteropelvic Junction (UPJ) Obstruction

The main job of the kidney is to filter the blood, remove waste products and deliver waste products (urine) through the ureter to the bladder. But what happens when the area where the ureter and the renal pelvis meet becomes blocked in children? The following information should help you recognize this problem before it causes serious damage.

What happens under normal conditions?

Kidneys produce urine by filtering the blood and removing wastes, salts and water. The urine must then drain from the kidney through an internal collecting system that ends in a funnel-shaped structure called the renal pelvis and into a natural tube called the ureter. Each kidney must have at least one functional ureter (some have two) to carry the urine from the kidney to the bladder.

What is ureteropelvic junction (UPJ) obstruction?

The most common cause of obstruction (blockage) in the urinary tract in children is a congenital obstruction at the point where the ureter joins the renal pelvis — the ureteropelvic junction (UPJ). This problem occurs in approximately one in 1,500 children. These obstructions develop prenatally as the kidney is forming and today most are diagnosed on prenatal ultrasound screening. In UPJ obstruction, the kidney produces urine at a rate that exceeds the amount of urine able to drain out of the renal pelvis into the ureter and this causes accumulation of urine within the kidney. This accumulation, also called hydronephrosis, is easily visible on ultrasound and often allows the physician to predict the presence of UPJ obstruction before the baby is born.

Although encountered less frequently in adults, UPJ obstruction may occur as a result of kidney stones, previous surgery or disorders that can cause inflammation of the upper urinary tract.

What are the symptoms of ureteropelvic junction (UPJ) obstruction?

Since the development of ultrasound and its widespread use to screen the unborn child, most UPJ obstructions are identified long before birth. After birth, symptoms of UPJ obstruction may be an abdominal mass, a urinary tract infection with fever, flank pain especially with increased fluid intake, stones and bloody urine. Patients with UPJ obstruction may also have pain without an infection. Some UPJ obstructions are irregular in nature and urine may drain normally at one time and be completely obstructed at others producing sporadic pain.

How is ureteropelvic junction (UPJ) obstruction diagnosed?

While ultrasound is a very useful screening test it is not diagnostic of UPJ obstruction. In order to make the diagnosis it is necessary to perform a functional test or one that measures the ability of the kidney to produce and drain urine. The classic examination is called the intravenous pyelogram (IVP). In this test, a dye is injected into the blood stream and the kidneys remove this substance from the blood. The dye passes into the urine and eventually out of the bladder. The dye is visible on X-ray and the physician can see the shape of the kidney, renal pelvis and ureter. While IVPs continue to be helpful, a more useful examination in children is the furosemides renal scan. This test is done in a similar fashion to the excretory urogram except that a radioactive material is used instead of X-ray dye. The material can be followed with a special camera and this test can give more accurate information about kidney function and drainage.

How is ureteropelvic junction (UPJ) obstruction treated?

Before considering treatment it is important to understand that poor drainage through the UPJ in infants and young children less than 18 months of age may be temporary. This subject remains controversial and is open to the opinions of different experts. Many infants with good kidney function and poor drainage will have a dramatic improvement of drainage over the first few months of life while some will not improve and others will worsen. For this reason, in this age range, some patients with hydronephrosis (fluid-filled enlargement of the kidney) are watched with repeat CT scans and ultrasounds. This spontaneous improvement usually takes place only within the first 18 months of life. Once the diagnosis of UPJ obstruction is established and there is no further reasonable chance of improvement, the condition requires surgical treatment.

The classic treatment of UPJ obstruction is an open operation to remove the UPJ and to reattach the ureter to the pelvis of the kidney creating a wide junction between the two. This operation, called a pyeloplasty, allows rapid and easy drainage of urine produced by the kidney and relieves symptoms and the risk of infection. The procedure usually takes a few hours and has a success rate in excess of 95 percent with one operation. Hospitalization after surgery depends on age of the patient. There are a variety of drainage tubes utilized to promote healing and their use is dependent on the surgeon's preference. The incision is usually just below the ribs and just behind a line that would pass from the patient's arm to their leg on the affected side. The incision is usually two to three inches long.

Newer treatment of UPJ obstruction involves minimally invasive surgery. There are two options, a laparoscopic pyeloplasty and an internal incision of the UPJ. Laparoscopic surgery is done by placing several instruments through the abdominal wall and performing the surgical procedure. This procedure is most often done through the abdominal cavity and has the disadvantage of potentially causing scarring or adhesions within the abdomen. Surgeons also cannot utilize techniques that are as delicate in a laparoscopic as in an open procedure. The clear advantages of laparoscopic surgery are less pain and nausea especially in older children and adults. Success rates of laparoscopic pyeloplasty are just being determined but we would expect that they would approach the effectiveness of open surgery with time. The second option is to insert a wire through the ureter and use it to cut the tight and narrow UPJ from the inside. A special ureteral drain is then left in place for several weeks and then removed. The UPJ heals in a more open manner in most patients but the treatment may need to be repeated and success rates are clearly less than those of open surgery. The advantages of this procedure are less pain and nausea.

What can be expected after treatment for ureteropelvic junction (UPJ) obstruction?

After repair of UPJ obstruction, there is usually swelling of the ureter and continued poor drainage of the kidney for a period of time. This usually changes as the area heals. The surgeon usually obtains a functional test, a few weeks after the procedure, to evaluate how well the kidney is working. Patients usually recover quickly from any of the procedures but some have pain for a few days following surgery and occasionally a drainage tube must be left in place to help drain the kidney while it heals. The appearance of the kidney can continue to improve for years but usually it never looks normal on ultrasound or other studies. Once repaired, a UPJ obstruction almost never recurs. There is nothing that the family can do to prevent further problems with the kidney. Patients may have a slightly increased risk of developing stones and infection throughout their lives because many of the kidneys still contain some pooled urine even though their overall drainage is improved after surgery.

Frequently asked questions:

What did I do during pregnancy to cause this problem in my child?

Nothing. It is not yet known what the causes are or how it can be prevented.

Do my other children need screening for UPJ obstruction?

Only if they show symptoms. Occasionally there have been cases where a family may have several members suffering from UPJ obstructions but the vast majority are individual cases.

Is my baby in pain because of a UPJ obstruction?

The general belief is that most children are not in pain unless the urine becomes infected or the obstruction becomes worse.

Can my child participate in athletics later?

If the other kidney is normal and the affected kidney responds to treatment most experts feel that children can participate in athletics normally.

Can the obstruction come back?

Not usually. Once it is repaired almost all kidneys continue to work well. Occasionally a child with a partial obstruction as an infant that improved without surgery will return later with symptoms that require surgery.



Reviewed January 2011

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Ureteropelvic Junction (UPJ) Obstruction 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.

  • abdominal: in the abdomen, the cavity of this part of the body containing the stomach, intestines and bladder.

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

  • congenital: Present at birth.

  • CT scan: Also known as computerized tomography, computerized axial tomography or CT scan. A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce cross-sectional images of the body. Shows detailed images of any part of the body, including bones, muscles, fat and organs. CT scans are more detailed than general X-rays.

  • diagnosis: The process by which a doctor determines what disease or condition a patient has by studying the patient's symptoms and medical history, and analyzing any tests performed (e.g., blood tets, urine tests, brain scans, etc.).

  • excretory: unwanted or undigestable matter.

  • excretory urogram: Also known as intravenous pyelogram. A test that uses X-rays and contrast dye to take pictures of the kidneys, ureter and bladder.

  • flank: The area on the side of the body between the rib and hip.

  • furosemides renal scan: Kidney scan using a diuretic.

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

  • 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.

  • 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.

  • inflammation: Swelling, redness, heat and/or pain produced in the area of the body as a result of irritation, injury or infection.

  • 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.

  • kidney stone: A stone that develops from crystals that form in urine and build up on the inner surfaces of the kidney, in the renal pelvis or in the ureters. (Also see nephrolithiasis.)

  • 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.

  • laparoscopic: 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.

  • laparoscopic pyeloplasty: Repairing kidney blockage by using a laparoscope, 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.

  • laparoscopic surgery: Surgery performed with an instrument in the shape of a tube that is inserted through small cuts. Using a small video camera and a few customized instruments, the surgeon can work in many body cavities without dividing skin from muscle thus reducing recovery time and complications.

  • liver: A large, vital organ that secretes bile, stores and filters blood, and takes part in many metabolic functions, for example, the conversion of sugars into glycogen. The liver is reddish-brown, multilobed, and in humans is located in the upper right part of the abdominal cavity.

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

  • pelvic: Relating to, involving or located in or near the pelvis.

  • pelvis: The bowl-shaped bone that supports the spine and holds up the digestive, urinary and reproductive organs. The legs connect to the body at the pelvis.

  • pregnancy: The condition of being pregnant.

  • prenatal: Before birth.

  • prenatally: Before birth.

  • pyeloplasty: Surgical reconstruction of the renal pelvis to correct a blockage.

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

  • renal: Pertaining to the kidneys.

  • renal pelvis: The basin into which the urine formed by the kidneys is excreted before it travels to the ureters and bladder.

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

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

  • 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.

  • UPJ: Also referred to as ureteropelvic junction. A blockage of a ureter in the region where the ureter enters the pelvis. Most often caused by a kidney stone.

  • 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.

  • ureteropelvic junction: Also referred to as UPJ. A blockage of a ureter in the region where the ureter enters the pelvis. Most often caused by a kidney stone.

  • 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.

  • 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.

Ureteropelvic Junction (UPJ) Obstruction Anatomical Drawings

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