Hydronephrosis in Children in Lebanon — موه الكلية عند الأطفال

What Is Hydronephrosis in Children?

Hydronephrosis refers to the swelling (dilation) of a kidney's collecting system — the renal pelvis and calyces — caused by a buildup of urine. It is one of the most commonly detected abnormalities on prenatal ultrasound, found in approximately 1–2% of all pregnancies. Hydronephrosis is not a disease itself but a sign that urine is not draining properly from the kidney. The severity ranges from mild dilation that resolves on its own to significant obstruction that, if left untreated, can damage the developing kidney. In most cases, especially when detected before birth, hydronephrosis is mild and requires only observation.

Causes and Grading

The most common cause of hydronephrosis in infants is ureteropelvic junction (UPJ) obstruction — a narrowing where the kidney connects to the ureter. Other causes include vesicoureteral reflux (urine flowing backward from the bladder to the kidney), ureterovesical junction obstruction, posterior urethral valves (in boys), and less commonly, ectopic ureters or ureteroceles. Hydronephrosis is graded using the Society for Fetal Urology (SFU) system on a scale of 1 to 4: Grade 1 involves mild dilation of the renal pelvis only. Grade 2 shows dilation extending into the calyces. Grade 3 demonstrates further calyceal dilation with thinning of the kidney tissue. Grade 4 represents severe dilation with significant thinning of the renal parenchyma. This grading helps guide decisions about monitoring versus intervention.

Prenatal Detection and Postnatal Evaluation

Most cases of hydronephrosis are first identified during routine prenatal ultrasound, typically at the 18–20 week anatomy scan. When hydronephrosis is detected before birth, the pregnancy is monitored with follow-up ultrasounds but rarely requires intervention before delivery. After birth, the newborn should have a postnatal ultrasound — usually performed after the first 48 hours of life, because earlier scans may underestimate the degree of dilation due to normal newborn dehydration. Depending on the ultrasound findings, additional studies may be ordered, including a voiding cystourethrogram (VCUG) to rule out vesicoureteral reflux, and a MAG3 renal scan to assess kidney function and drainage.

When to See a Pediatric Urologist

You should consult a pediatric urologist if prenatal ultrasound shows moderate to severe hydronephrosis (SFU grade 3–4), if postnatal ultrasound confirms persistent dilation, if your child has urinary tract infections associated with hydronephrosis, or if there are concerns about kidney function. Even in mild cases, an initial evaluation by a specialist provides reassurance and establishes an appropriate monitoring plan. Dr. Kallas Chemaly evaluates each case individually and explains the findings and plan clearly to parents in Arabic, French, or English.

Treatment: Observation vs. Pyeloplasty

The majority of children with mild to moderate hydronephrosis (SFU grade 1–2) are managed with observation — serial ultrasounds to track the dilation over time. Many of these cases resolve spontaneously within the first one to two years of life. Prophylactic antibiotics may be prescribed to prevent urinary tract infections during the monitoring period. When hydronephrosis is caused by a significant UPJ obstruction with declining kidney function or worsening dilation, pyeloplasty is the treatment of choice. This surgery removes the obstructed segment and reconstructs a wide, open connection between the kidney and ureter. Pyeloplasty has a success rate exceeding 95% and is one of the most reliable operations in pediatric urology.

Dr. Kallas Chemaly's Approach

Dr. Kallas Chemaly brings fellowship training from three European centers of excellence — Hôpital Robert-Debré (Paris), Queen Fabiola Children's Hospital (Brussels), and Hôpital Femme Mère Enfant (Lyon) — where he managed high volumes of hydronephrosis cases, from prenatal counseling through postnatal management and surgical correction. He emphasizes a measured, evidence-based approach: avoiding unnecessary surgery while acting decisively when kidney function is at risk. For families whose child was diagnosed prenatally, he provides clear guidance from the very first consultation, reducing anxiety and ensuring no critical steps are missed.

References

• Children's National Hospital: Pediatric Hydronephrosis
• MedlinePlus Medical Encyclopedia: Hydronephrosis of one kidney