UPJ obstruction Health Article

Definition

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.

Alternative Names

Ureteropelvic junction obstruction; UP junction obstruction; Obstruction of the ureteropelvic junction

Causes, incidence, and risk factors

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.

Symptoms

There may not be any symptoms. When symptoms occur, they may include:

• Back or flank pain
• Bloody urine (hematuria)
• Lump in the abdomen (abdominal mass)
• Kidney infection
• Poor growth in infants (failure to thrive)
• Urinary tract infection, usually with fever
• Vomiting

Signs and tests

An ultrasound during pregnancy may show kidney problems in the unborn baby.

Tests after birth may include:

• BUN
• Creatinine clearance
• CT scan
• Electrolytes
• IVP
• Nuclear scan of kidneys
• Voiding cystourethrogram