Ureteropelvic Junction (UPJ) Obstruction is a condition where a blockage occurs at the junction where the ureter meets the renal pelvis of the kidney. This obstruction impedes the flow of urine from the kidney to the bladder, leading to kidney swelling (hydronephrosis) and potential kidney damage.

UPJ Obstruction has been recognized, in various forms, for over a century.  In the early 20th century, surgical techniques were developed to correct the obstruction. Advancements in prenatal ultrasound technology in recent decades have allowed for earlier detection, even before birth. This has significantly refined the approaches to managing and treating this condition. While most UPJ obstruction improves with time, some require surgery. For some patients, robot assisted laparoscopic surgery allows for repair with excellent outcomes and relatively fast recovery compared to traditional open surgery.


UPJ Obstruction can be congenital (present at birth) or acquired. Congenital UPJ obstruction is caused by an abnormal narrowing at or high insertion point of the ureter at the UPJ or sometimes by a blood vessel crossing and causing the ureter to kink. Acquired UPJ obstruction can result from kidney stones, scarring, or previous surgery.

Risk Factors

  • Family history of congenital urinary tract anomalies.
  • Certain genetic conditions or syndromes.
  • Previous urinary tract surgeries or infections.


Effects of UPJ Obstruction can range from asymptomatic, mild cases to severe, life-threatening conditions. If left untreated, the chronic pressure build-up can cause permanent kidney damage.

Hydronephrosis (swelling of the kidney due to urine buildup).

Kidney stones due to stagnant urine.

Recurrent urinary tract infections.

Kidney damage or decreased kidney function.


There are no specific preventive measures for congenital UPJ obstruction. However, early diagnosis and treatment are essential to allow proper monitoring and sometimes surgical intervention to prevent complications. Regular prenatal care can help detect UPJ obstruction before birth.


When to see a doctor