What is pyeloplasty?

Pyeloplasty is surgery used to correct a condition called ureteropelvic junction (UPJ) obstruction.

What is ureteropelvic junction (UPJ) obstruction?

UPJ obstruction blocks the flow of urine out of the kidney into the ureter. The ureter is a tube attaching the kidney to the bladder. The blockage is at the point where the kidney (renal pelvis) attaches to the ureter (ureteropelvic junction).

What causes UPJ obstruction?

UPJ obstruction mostly happens in children. When the condition is present from birth, it is called a congenital condition. Most often this is how the condition forms. The blockage happens when the area between the ureter and part of the kidney becomes too narrow. This condition happens as the kidney is forming. It can result in a damaged kidney from urine buildup and increased pressure in the kidney. Usually, only one kidney is affected.

Other causes of blockage for adults and children include:

  • Abnormal blood vessel over the ureter
  • Scar tissue
  • Infection
  • Earlier treatments for a blockage
  • Kidney stones

How is UPJ obstruction diagnosed?

UPJ obstruction is typically found with an ultrasound before the baby is born. Sometimes the blockage will not show until after birth. Mostly, the condition happens in individuals. In some cases, several members of a family have the condition.

After birth, tests can be performed including:

  • CT scan
  • CT urogram (scan of both kidneys with contrast)
  • Ultrasound
  • Blood test
  • Urine and blood test
  • Electrolytes
  • Nuclear scan of kidneys
  • X-ray of kidneys, bladder, ureters
  • Voiding cystourethrogram (X-ray of bladder while it is emptying)

What are the symptoms of UPJ obstruction?

During UPJ obstruction, kidneys can become damaged from urine buildup.

Symptoms of UPJ obstruction include:

  • Abdominal mass
  • Urinary tract infection
  • Back or flank pain
  • Bloody urine
  • Kidney infection
  • Poor growth in infants
  • Vomiting

Last reviewed by a Cleveland Clinic medical professional on 08/21/2017.


  • Kausik, Sankar, & Segura, Joseph W... (2003). Surgical management of ureteropelvic junction obstruction in adults. International braz j urol, 29(1), 3-10. dx.doi.org Accessed 8/29/2017.

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