UPJ obstructionUreteropelvic junction obstruction; UP junction obstruction; Obstruction of the ureteropelvic junction
Ureteropelvic junction (UPJ) obstruction is a blockage at the point where part of the kidney attaches to one of the tubes to the bladder (ureters). This blocks the flow of urine out of the kidney.
UPJ obstruction mostly occurs in children. It often happens when a baby is still growing in the womb. This is called a congenital condition (present from birth). The blockage is caused when there is a narrowing of area between the ureter and the part of the kidney called the renal pelvis. Urine can build up and damage the kidney as a result.
The condition can also be an abnormal blood vessel over the ureter. In older children and adults, the problem may be due to scar tissue, infection, earlier treatments for a blockage, or kidney stones.
UPJ obstruction is the cause of most urinary blockages in children. It is now commonly found before birth with ultrasound tests. In some cases, the condition may not show up until after birth. Symptoms may include an abdominal mass or a urinary tract infection .
An abdominal mass is swelling in one part of the belly area (abdomen).
Urinary tract infection
A urinary tract infection, or UTI, is an infection of the urinary tract. The infection can occur at different points in the urinary tract, including...
Surgery may be needed early in life if the problem is severe. Most of the time, surgery is not needed until later. Some cases do not require surgery at all.
There may not be any symptoms. When symptoms occur, they may include:
Flank pain is pain in one side of the body between the upper belly area (abdomen) and the back.
- Bloody urine (hematuria)
- Lump in the abdomen (abdominal mass)
- Kidney infection
- Poor growth in infants (failure to thrive)
- Urinary tract infection, usually with fever
Exams and Tests
An ultrasound during pregnancy may show kidney problems in the unborn baby.
Tests after birth may include:
BUN stands for blood urea nitrogen. Urea nitrogen is what forms when protein breaks down. A test can be done to measure the amount of urea nitrogen ...
The creatinine clearance test helps provide information about how well the kidneys are working. The test compares the creatinine level in urine with...
- CT scan
Electrolytes are minerals in your blood and other body fluids that carry an electric charge. Electrolytes affect how your body functions in many ways...
- less commonly used
An intravenous pyelogram (IVP) is a special x-ray exam of the kidneys, bladder, and ureters (the tubes that carry urine from the kidneys to the bladd...
- CT urogram - scan of both kidneys and ureters with IV contrast
Nuclear scan of kidneys
Nuclear scan of kidneys
A renal scan is a nuclear medicine exam in which a small amount of radioactive material (radioisotope) is used to measure the function of the kidneys...
A voiding cystourethrogram is an x-ray study of the bladder and urethra. It is done while the bladder is emptying.
Surgery to correct the blockage allows urine to flow normally. Most of the time, open (invasive) surgery is performed in infants. Adults may be treated with less-invasive procedures. These procedures involve much smaller surgical cuts than open surgery, and may include:
- Endoscopic (retrograde) technique does not require a surgical cut on the skin. Instead, a small instrument is placed into the urethra. This allows the surgeon to open the blockage from the inside.
- Percutaneous (antegrade) technique involves a small surgical cut on the side of the body between the ribs and the hip.
- Pyeloplasty removes scar tissue from the blocked area and connects the healthy part of the kidney to the healthy ureter.
Laparoscopy has also been used to treat UPJ obstruction in children and adults who have not had success with other procedures.
A tube called a stent may be placed to drain urine from the kidney until the surgery heals. A nephrostomy tube, which is placed in the side of the body to drain urine, may also be needed for a short time after the surgery. This type of tube may also be used to treat a bad infection before surgery.
A stent is a tiny tube placed into a hollow structure in your body. This structure can be an artery, a blood vessel, or something such as the tube t...
Detecting and treating the problem early can help prevent future kidney damage. UPJ obstruction diagnosed before birth or early after birth may actually improve on its own.
Most children do well and have no long-term problems. Serious damage may occur in people who are diagnosed later in life.
Long-term outcomes are good with current treatments. Pyeloplasty has the best long-term success.
If untreated, UPJ obstruction can lead to permanent loss of kidney function ( kidney failure ).
Acute kidney failure is the rapid (less than 2 days) loss of your kidneys' ability to remove waste and help balance fluids and electrolytes in your b...
Kidney stones or infection may occur in the affected kidney, even after treatment.
When to Contact a Medical Professional
Call the health care provider if your infant has:
- Bloody urine
- A lump in the abdomen
- Indications of back pain or pain in the flanks (the area towards the sides of the body between the ribs and the pelvis)
Elder JS. Obstruction of the urinary tract. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics .19th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 534.
Frokiaer J, Zeidel ML. Urinary tract obstruction. In: Taal MW, ed. Brenner and Rector's The Kidney . 9th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 35.
Pais VM, Strandhoy JW, Assimos DG. Pathophysiology of urinary tract obstruction. In: Wein AJ, ed. Campbell-Walsh Urology . 10th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 41.
Singh I, Standhoy JW, Assimos DG. Pathophysiology of urinary tract obstruction. In: Wein AJ, ed. Campbell-Walsh Urology . 10th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 40.
Kidney anatomy - illustration
The kidneys are responsible for removing wastes from the body, regulating electrolyte balance and blood pressure, and stimulating red blood cell production.
Review Date: 6/29/2015
Reviewed By: Jennifer Sobol, DO, urologist at the Michigan Institute of Urology, West Bloomfield, MI. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.