Antenatal hydronephrosis is one of the most commonly detected abnormalities during prenatal ultrasounds. It refers to the swelling or dilation of the kidney(s) in the fetus due to a buildup of urine, typically caused by a blockage or reflux in the urinary tract. While it may sound alarming, many cases resolve on their own without intervention. This blog explores the causes, diagnosis, and management of antenatal hydronephrosis to help parents understand the condition and its implications.
What Is Antenatal Hydronephrosis?
Hydronephrosis refers to the swelling of the kidneys caused by an obstruction or backup of urine. When it is detected during pregnancy through routine ultrasounds, it is referred to as antenatal hydronephrosis. This condition can affect one kidney (unilateral) or both kidneys (bilateral).
Causes of Antenatal Hydronephrosis
Several underlying conditions can lead to antenatal hydronephrosis, including:
1. Pelvi-Ureteric Junction Obstruction (PUJO)
• A blockage at the junction where the kidney connects to the ureter (tube carrying urine to the bladder).
2. Vesico-Ureteral Reflux (VUR)
• A condition where urine flows backward from the bladder to the kidneys.
3. Posterior Urethral Valves (PUV)
• An abnormality in boys where a membrane blocks urine flow in the urethra.
4. Ectopic Ureter
• When the ureter connects to an unusual location, disrupting normal urine flow.
5. Ureterocele
• A swelling at the end of the ureter that blocks urine flow.
How Is It Diagnosed?
1. Prenatal Ultrasound
• Hydronephrosis is typically identified during routine ultrasounds in the second or third trimester of pregnancy. The degree of swelling is assessed based on the size of the renal pelvis (part of the kidney that collects urine).
2. Postnatal Imaging
After birth, additional tests may be required to confirm the diagnosis and determine the cause. These may include:
• Ultrasound: To evaluate the size and condition of the kidneys.
• Voiding Cystourethrogram (VCUG): To check for reflux of urine into the kidneys.
• Renal Scan: To assess kidney function and drainage.
Severity Levels
Antenatal hydronephrosis is classified based on the degree of swelling:
• Mild: Minimal dilation of the kidney; often resolves on its own.
• Moderate: Requires monitoring and postnatal evaluation.
• Severe: Indicates significant obstruction or reflux; may require surgical intervention.
Management and Treatment
1. During Pregnancy
• In most cases, antenatal hydronephrosis does not require intervention during pregnancy. Regular ultrasounds are conducted to monitor the condition.
2. After Birth
• Observation: Many mild cases resolve spontaneously within the first year of life.
• Antibiotics: In cases with a risk of urinary tract infections (UTIs), low-dose antibiotics may be prescribed as a preventive measure.
• Surgery: Severe cases caused by PUJO, PUV, or other structural abnormalities may require surgical correction to restore normal urine flow and prevent kidney damage.
Complications if Left Untreated
If severe antenatal hydronephrosis is not managed, it may lead to:
• Recurrent urinary tract infections.
• Impaired kidney function.
• Long-term kidney damage or scarring.
Prognosis
The outlook for children with antenatal hydronephrosis is generally positive. Most cases resolve on their own or with minimal intervention. For those requiring surgery, advances in pediatric urology have made these procedures safe and effective, ensuring a good quality of life.
Final Thoughts
Antenatal hydronephrosis can be concerning for parents, but early detection and proper management significantly improve outcomes. If your baby has been diagnosed with this condition, stay in close contact with your pediatrician and a pediatric urologist to ensure timely monitoring and treatment.
Have questions or concerns? Contact our expert pediatric surgeons for personalized guidance and care.