Ureteropelvic junction (UPJ) obstruction

Reviewed by Michael Stifelman, M.D. and Ojas Shah, M.D.

More information on ureteropelvic junction obstruction

Definition, causes and risk factors

The ureteropelvic junction is the area where the renal pelvis (the part of the kidney where urine collects) meets the ureter. A ureteropelvic junction (UPJ) obstruction is a blockage in this area. Normally, the kidneys clean and filter the blood and produce urine that carries waste products out of the body. The ureters are the ducts that carry urine from the kidneys to the bladder. When a UPJ obstruction is present, the kidney becomes dilated (hydronephrotic), which may lead to deterioration in kidney function over time, development of kidney or urinary tract infections, and possibly formation of kidney stones.

UPJ obstruction is more common in children than in adults. It is typically caused by a congenital anomaly (which means it is present at birth). For example, when a blood vessel crosses the ureter and causes kinking of the ureter, or when a segment of the ureter does not contract properly, it can cause an obstruction of the kidney.

In adults, obstructions may result from injury during surgery or from scarring from a past surgery. They may also be caused by kidney stones, upper urinary tract inflammation or a tumor.

Symptoms and diagnosis

In children, UPJ obstructions are frequently diagnosed prenatally by ultrasound imaging.

After birth, symptoms in children may include

  • Pain in the side or lower back
  • Poor feeding
  • Blood in the urine
  • Kidney stones
  • High blood pressure
  • Frequent urinary tract infections
  • An abdominal mass

Sometimes UPJ obstructions do not result in any symptoms.


In infants and young children, obstructions may improve or resolve spontaneously during the first 18 months of life. Your doctor may monitor the blockage by ultrasound, renal scan (a nuclear medicine study) and/or CT scan during this period.

In both adults and children, in some cases, reconstructive surgery may be necessary to "bypass" the blocked area by removing the blockage and reconnecting the ureter to the kidney in a different location—an operation known as pyeloplasty. At NYU Urology Associates, we focus on using the latest technologies, including robotic surgery, to maximize outcomes while minimizing pain and discomfort. Our physicians are known internationally for their research on robotic dismembered pyeloplasty and robotic ureteral reconstruction. Patients typically leave the hospital two days after undergoing these procedures.

Surgery may also be performed endoscopically, where a tiny flexible telescope (an endoscope) is passed through the ureter or through a percutaneous nephrostomy tube, and a laser is used to widen the narrowed area (an operation called endopyelotomy). Although this method is effective in some cases, in our experience, this technique is less successful than dismembered pyeloplasty and is typically used only in certain clinical scenarios.

Additional information on ureteropelvic junction obstruction

Make an appointment with an NYU urologist who treats ureteropelvic junction obstruction

Watch videos of surgical treatments for UPJ obstruction

Related publications by NYU urologists

  • Hyams ES, Kanofsky JA, Stifelman MD. Laparoscopic Doppler technology: applications in laparoscopic pyeloplasty and radical and partial nephrectomy. Urology. 71(5):952-6, 2008.
  • Mufarrij PW; Shah OD; Berger AD; Stifelman MD. Robotic Reconstruction of the Upper Urinary Tract. Journal of urology, 2007 Nov;178(5):2002-5.
  • Hyams, ES; Stifelman, MD. Laparoscopic Doppler technology: Applications in laparoscopic pyeloplasty, radical and partial nephrectomy. Journal of endourology, 2007 OCT;21(1):A136-A136
  • Mufarrij, P; Berger, A; Lipkin, M; Stifelman, M; Shah, O. Laparoscopic pyeloplasty with pyelolithotomy for treatment of concomitant ureteropelvic junction obstruction and kidney stones [Abstract]. Journal of endourology, 2007 OCT;21(1):A143-A143
  • Mufarrij, P; Berger, A; Lipkin, M; Shah, O; Stifelman, M. Robotic pyeloplasty for secondary versus primary ureteropelvic junction obstruction [Abstract]. Journal of endourology, 2007 OCT;21(1):A143-A143
  • Palese MA, Muver R, Phillips CK, Dinlenc C, Stifelman MD, DelPizzo, JJ. Robot-assisted laparoscopic dismembered pyeloplasty. JSLS. 9(3):252-7, 2005.
  • Palese MA, Stifelman MD, Munver R, Sosa RE, Philipps CK, Dinlenc C, Del Pizzo JJ. Robot-assisted laparoscopic dismembered pyeloplasty: a combined experience. J Endourology. 19(3):382-6, 2005.

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.