UPJ Obstruction in Children in Lebanon — انسداد الوصل الحالبي الحويضي

What Is UPJ Obstruction?

Ureteropelvic junction (UPJ) obstruction is a condition where the flow of urine is blocked or restricted at the point where the renal pelvis (the funnel-shaped part of the kidney that collects urine) connects to the ureter (the tube that carries urine to the bladder). It is the most common cause of significant hydronephrosis (swelling of the kidney) in children. The obstruction can be caused by an intrinsic narrowing of the ureter, a kink, or an abnormal blood vessel (crossing vessel) that compresses the junction. UPJ obstruction is frequently detected before birth during routine prenatal ultrasound, making it one of the most commonly diagnosed urological conditions in infants.

Signs, Symptoms, and Prenatal Detection

Most cases of UPJ obstruction are detected prenatally when a routine ultrasound shows dilation of the kidney (hydronephrosis) in the fetus. After birth, many infants have no symptoms and the condition is confirmed with postnatal ultrasound. In older children or those not diagnosed prenatally, symptoms may include flank or abdominal pain (especially after drinking large amounts of fluid), urinary tract infections, blood in the urine, or a palpable abdominal mass in newborns. Some children experience intermittent pain that corresponds to episodes of impaired drainage.

Diagnosis: Imaging and Functional Studies

After the initial ultrasound confirms hydronephrosis, further evaluation is needed to determine the severity of the obstruction and its impact on kidney function. The MAG3 diuretic renogram is the gold-standard functional study — it uses a small amount of radioactive tracer to measure how well each kidney drains and what percentage of overall kidney function each side contributes. A voiding cystourethrogram (VCUG) may also be performed to rule out vesicoureteral reflux as a contributing factor. Together, these tests allow the pediatric urologist to distinguish between obstruction that requires surgery and hydronephrosis that can be safely observed.

Observation vs. Surgery: When Is Intervention Needed?

Not every child with UPJ obstruction needs surgery. Mild to moderate hydronephrosis with preserved kidney function is often monitored with serial ultrasounds and repeat renograms. Many of these cases improve or stabilize on their own, particularly when detected prenatally. Surgery is recommended when there is worsening hydronephrosis, a decline in differential kidney function (typically below 40%), recurrent urinary tract infections, or significant pain. The decision is based on objective data — not a single test, but the trend over time.

Pyeloplasty: The Standard Surgical Treatment

When surgery is indicated, pyeloplasty is the procedure of choice. The surgeon removes the narrowed or obstructed segment of the UPJ and reconstructs the connection between the renal pelvis and the ureter, creating a wide, unobstructed drainage pathway. The Anderson-Hynes dismembered pyeloplasty is the most commonly performed technique and has a success rate exceeding 95%. Pyeloplasty can be performed through a small flank incision (open approach) or laparoscopically, depending on the child's age, size, and anatomy. A temporary ureteral stent or nephrostomy tube may be placed to support healing and is typically removed within a few weeks.

Dr. Kallas Chemaly's Approach to UPJ Obstruction

Dr. Kallas Chemaly trained in pyeloplasty — both open and laparoscopic — at leading European pediatric surgery centers including Robert-Debré (Paris), Queen Fabiola Children's Hospital (Brussels), and HFME (Lyon). He takes a data-driven approach: each child undergoes thorough imaging and functional assessment before any treatment decision is made. For cases that require surgery, he selects the approach best suited to the child's anatomy and age. He explains each step to parents in their preferred language (Arabic, French, or English) and provides close postoperative follow-up to ensure optimal outcomes. His goal is straightforward — protect the kidney, relieve the obstruction, and minimize the burden on the child and family.

References

• HealthyChildren.org: Ureteropelvic Junction Obstruction
• Children's National Hospital: Pediatric Congenital Ureteropelvic Junction Obstruction
• MedlinePlus Medical Encyclopedia: Ureteropelvic junction obstruction