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Pediatric – Ureteropelvic Junction Obstruction (UPJ)

What is Ureteropelvic Junction Obstruction (UPJ)?

UPJ obstruction develops when the meeting point of the ureter between the kidney pelvis and the ureter are located, become abnormally small. This narrowed ureter affects the normal flow of urine through the ureter into the bladder. This results in the urine becoming accumulated, which causes ‘Hydronephrosis’. This causes the renal pelvis to expand and become dilated.

The magnitude of the obstruction at the Ureteropelvic junction is different from patient to patient, and ranges from mild to severe. Generally, mild UPJ obstruction does not cause injury to the kidney or affect its normal functioning. Mild UPJ may result in UTI (urinary tract infection). In case the obstruction is severe, there is a risk of serious renal damage or impairing of the kidney’s functioning.


The most common cause of UPJ obstruction is seen as a birth defect, mostly in young children. This is often the result of abnormal development of the muscles surrounding the UPJ. It may also result due to an abnormality in the position and structure of the kidney, ureter and the renal blood vessels.
When the child is considerably grown up, UPJ may result in:

  • Inflammation which compresses the ureter

  • Formation of scar tissue in the renal cavity (called ‘retroperitoneal fibrosis’)

  • Kidney stones

  • Scar tissue from an earlier surgical procedure for treatment of UPJ obstruction


Common symptoms of UPJ obstruction include:

  • Back ache

  • Hematuria (blood in the urine)

  • Failure to develop

  • Pain in the flank

  • Abnormal mass in the flank

  • Pyelonephritis (kidney infection)

  • UTI (urinary tract infection)


Generally, UPJ obstruction is detected by prenatal ultrasound. The kidney of the fetus and the renal system are mostly detected in the prenatal ultrasound at around 15 weeks into the pregnancy.

Hydronephrosis is detected initially in the ultrasound which indicates towards the presence of an obstruction in the flow of urine. Later on, follow-up ultrasound is regularly scheduled during the latter stages of the pregnancy and even after the birth of the child.

A pediatric surgeon is ideal for diagnosing the symptoms of UPJ obstruction. The pediatric surgeon may advise the following diagnostic tests to the child:

  • Renal bladder ultrasound – This is mostly the initial test which is advised. It is useful for detecting the dilation of the renal pelvis and identifies its risk of affecting the functions of the kidney. This also helps to designate the condition as mild, moderate or severe.

  • Voiding cystourethrogram – This diagnostic test determines if vesicoureteral reflux or obstruction is present under the bladder.

  • IVP (intravenous Pyelogram)/Renal Scan – These tests are advised to determine the severity of the obstructed flow of urine from the kidney to the bladder.

Dependent on the results of the diagnostic tests the doctor will determine the severity of the condition and suggest a suitable treatment method for it.


Newborn children with UPJ obstruction and hydronephrosis are initially administered antibiotics to prevent the risk of infection. They are also monitored through a renal ultrasound every 3 to 6 months.

In case there is significant effect on the functioning of the kidneys due to the UPJ obstruction, the doctor may advise pyeloplasty (surgical treatment). This is useful in removing the obstruction, improve the flow of urine and also decrease the risk of damage to the kidney. This surgical procedure requires removal of the blockage and re-attaching the renal pelvis and the ureter. A stent may also be placed to keep the ureter opening wider and allow ideal draining of the urine from the kidney.

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