UPJ Obstruction

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Diagnosis & Evaluation


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The ureteropelvic junction is the anatomic location where the ureter (which is the tube the drains the urine from the kidney to the bladder) meets the kidney. Uretero-pelvic junction obstruction (UPJO) is defined as a functional or anatomic obstruction to urine flow from the kidney to the ureter which, if left untreated, results in symptoms or damage to the kidney. The incidence of UPJ O is 0.5% of all births. 80-90% of congenital UPJ Os are diagnosed antenatally (when the baby is in utero).


In the image on the right, the patient’s left kidney is affected by a UPJ obstruction




Causes of UPJ obstruction include primary or congenital causes or secondary/acquired causes . The most common cause of UPJ O is a “congenital” ureteral narrowing. This means a narrowing of the ureter that an individual is born with.  There can be a variety of reasons for congenital narrowing of the ureter. The most common secondary or acquired cause is a kidney stone which is lodged at the ureteropelvic junction. There are other less common secondary causes.


Diagnosis & Evaluation of UPJO


In the pediatric setting, 80-90% of patients will have a congenital UPJ O discovered antenatally. This is identified as dilation of the kidney (hydronephrosis ) seen on prenatal ultrasound . This diagnosis is often confirmed post-natally (after delivery) with the use of ultrasound as well as renogram evaluation. Similarly in the adult population the diagnosis is often made with ultrasound and renogram. Often this finding in adults is discovered incidentally when the patient is being investigated for some other medical issue.


The majority of patients present with an abnormal prenatal ultrasound. In older children or in adults presenting symptoms can include:

  • Abdominal or flank pain
  • Nausea and vomiting
  • Fever
  • Blood in the urine
  • Urinary tract infection associated with fever


When a prenatal diagnosis is known, postnatal evaluation includes:

  • Postnatal ultrasound at approximately 1 week of age to confirm the presence of a dilated kidney
  • MAG3 renogram in approximately 3-6 months of age to assess function and drainage of the kidney
  • Serial ultrasounds +/- repeat renograms will be ordered routinely every 6-12 months to assess changes of the kidney.

The frequency of imaging studies will depend on if the patient's having any symptoms.

When the patient presents later childhood or as an adult, evaluation includes:

  • Renal ultrasound
  • Renogram
  • Routine blood work to assess renal function
  • Possible urine culture if the patient is having problems with recurrent infections
  • Possible cystoscopy if the patient has had an episode of blood in the urine




The decision to treat ureteropelvic junction obstruction often requires multiple evaluations to assess whether or not the patient warrants surgical repair. The goal of treating UPJ obstruction is to preserve renal function and minimize symptoms of the obstruction. Often multiple imaging studies are used to determine that the patient has a problematic UPJ obstruction. Generally, the decision to proceed to surgery is not made quickly.


Indications for treating ureteropelvic junction obstruction include:

  1. Decline in renal function seen on renogram in the pediatric population
  2. Symptoms associated with UPJ obstruction – Pain, infection of the affected kidney, bleeding or stone formation in the affected kidney


Treatment is a surgical repair called a pyeloplasty. This is where the affected area of the ureter is identified and excised and the ureter is reattached to the kidney for better drainage. This type of surgery can be done in an open or laparoscopically. A stent was often left in place to allow the ureter to heal well to the kidney. The stent is removed at a later time once the repair has healed. Your urologist will then monitor you post-operatively and may repeat imaging study such as an ultrasound.

This image shows the affect area of a right kidney being excised and the ureter being re-attached to the right kidney over a stent. The stent will be removed later

On the Web

Children's Hospital of Philadelphia Information on UPJO


Last Edit: March 2013 Dr. J Mickelson