Ureteropelvic Junction Obstruction
Ureteropelvic junction is the part of the kidney where the ureter joins the renal pelvis. Normally, kidneys filter the blood and remove the waste products in the form of urine. This urine is drained through the renal pelvis into the ureters. Form the ureters the urine reaches the urinary bladder and is voided out through the urethra.
In case of ureteropelvic junction (UPJ) obstruction, the urine cannot flow properly from the renal pelvis to the ureters. This results in pooling of urine in the renal pelvis. The build up of urine can cause swelling of the kidneys (hydronephrosis) and if not treated, it may even damage the kidneys.
UPJ obstruction is usually a congenital condition though it may develop in adults post kidney stones.
How common is UPJ obstruction?
Antenatal ultrasonography shows that congenital Ureteropelvic junction obstruction may affect 1 in every 500 children. It is more common in boys. Left sided UPJ obstruction is more common than that on the right side. Bilateral UPJ obstruction is seen in 10% to 40% cases.
Cause of UPJ obstruction
Most of the cases of UPJ obstruction are congenital. This blockage usually occurs while the kidney is developing. In certain cases, it is prevalent in siblings.
In adults UPJ obstruction may take place after kidney stones or following swelling of the upper urinary tract.
Signs and symptoms of UPJ obstruction
Most of the cases are diagnosed before birth. The obstruction to the urine flow leads to swelling of the kidney. A swollen kidney can be easily seen during antenatal ultrasound.
Many cases of Ureteropelvic junctionobstruction which are not diagnosed before birth do not show any symptom. This is especially true in case of partial obstruction. In children who show symptoms, the common presenting features are:
- A palpable abdominal mass due to swollen kidney
- Urinary tract infection
- Pain in the flanks
- Stones in the kidney due to pooling of urine
- Blood in urine
- Nausea and vomiting
- Failure to thrive
It is believed that children do not present with symptoms unless the urine becomes infected.
Diagnosis of Ureteropelvic Junction obstruction
UPJ obstruction can be easily diagnosed with the help of ultrasound. Apart from ultrasound, several other tests are done to confirm the diagnosis and to assess the damage to kidneys.
Blood urea nitrogen (BUN) and creatinine tests are done.
Intravenous pyelography was done earlier to visualize the urinary tract. Nowadays, nuclear renal scan is done in its place.
Sometimes, when children present with acute pain in the ER, a CT scan reveals UPJ obstruction.
Treatment of UPJ obstruction
Treatment is not necessary in all cases. If the drainage is poor but the renal function is good and the child is less than 15 months of age, most surgeons prefer a wait and watch approach. Such children usually improve within a few months. However, if the renal function is also deteriorating, intervention becomes necessary.
Pyeloplasty: In this surgery, the UPJ is surgically removed, and the ureter is again attached to the renal pelvis after widening their orifice. This allows the urine to drain easily and provides relief from the symptoms.
Nowadays, laparoscopic pyeloplasty is also done to treat UPJ obstruction.