Ureteropelvic junction (UPJ) obstruction is a blockage in the area that connects the renal pelvis (part of the kidney) to one of the tubes (ureters) that move urine to the bladder.
UPJ obstruction generally occurs when a baby is still growing in the womb. This is called a congenital condition (present from birth). Most of the time, the blockage is caused when the connection between the ureter and the renal pelvis narrows. This causes urine to build up, damaging the kidney. The condition can also be caused when a blood vessel is located in the wrong position over the ureter. In older children and adults, UPJ obstruction can be due to scar tissue, infection, previous treatments for a blockage, or kidney stones.
UPJ obstruction is the most frequently diagnosed cause of urinary obstruction in children. It is now commonly diagnosed during prenatal ultrasound studies. In some cases, the condition isn’t seen until after birth. Children may have an abdominal mass or a urinary tract infection. The most severe cases of UPJ obstruction may require surgery early in life. However, the majority of cases may not require surgery until later in life, and some cases do not require surgery at all.
There may not be any symptoms. When symptoms occur, they may include:
- Back or flank pain
- Blood in 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:
- Creatinine clearance
- CT scan
- Nuclear scan of kidneys
- Voiding cystourethrogram
Surgery to correct the blockage allows urine to flow normally. Open (invasive) surgery is usually 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 and 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.
- Open pyeloplasty has been the gold standard treatment for ureteropelvic junction obstruction. It removes scar tissue from the blocked area and connects the healthy part of the kidney to the healthy ureter.
- Recently, laparoscopy has 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 patient heals. A nephrostomy tube, which is placed in the patient’s side to drain urine, may also be needed for a short time after the surgery. This type of tube may also used to treat severe infections before surgery.
Permanent loss of kidney function (kidney failure) is a possible complication of untreated UPJ obstruction. Even after treatment, the affected kidney may be at increased risk for infection or kidney stones.