Hydronephrosis

The urinary system helps the body get rid of waste and extra water by making and passing urine. It includes:

• Kidneys: Two bean-shaped organs that clean the blood and make urine.
• Ureters: Thin tubes that carry urine from each kidney down to the bladder.
• Bladder: A balloon-shaped organ that stores urine until it is ready to leave the body.
• Urethra: The small tube that carries urine from the bladder out of the body.

Hydronephrosis can happen for different reasons:

• Normal development: In many babies, a small amount of swelling is normal and often disappears before or soon after birth.
• A blockage (obstruction): There might be a narrowing where the kidney joins the ureter (the tube that carries urine to the bladder) — this is called a pelvi-ureteric junction (PUJ) obstruction.
• Slow drainage: The urine may be taking longer to flow from the kidney to the bladder.
• Bladder: A balloon-shaped organ that stores urine until it is ready to leave the body.
• Urethra: The small tube that carries urine from the bladder out of the body.

If your baby is diagnosed with hydronephrosis, you will be referred to a fetal medicine specialist for further checks and support.

Here’s what usually happens next:

• Detailed ultrasound scan: A specialist will look closely at your baby’s kidneys, bladder, and the amount of amniotic fluid around your baby.
• Regular monitoring: You will have follow-up scans during pregnancy to see if the swelling changes, improves, or becomes more noticeable.
• Additional tests (if needed): You may be offered invasive testing to check for chromosome or genetic conditions if the doctor thinks this may be linked.
• Planning the birth: The team will discuss the best place for you to give birth, which may be at a hospital with access to newborn and kidney specialists.
• After birth: Your baby will usually have a kidney ultrasound in the first few days or weeks to check if the hydronephrosis is still present.
• Referral (if needed): If the swelling remains, your baby may be referred to a paediatric kidney (paediatric nephrologist) or urinary specialist (paediatric urologist) for further tests or follow-up.

In many cases, the swelling gets better on its own, and your baby will just need regular scans and check-ups to make sure everything is developing normally.

Sometimes, babies with hydronephrosis are given a small daily dose of antibiotics to help prevent urinary tract infections (UTIs). This is called prophylactic antibiotics. Not all babies will need them and it will depend on the findings of your baby’s scan. Your baby’s doctor or specialist team will explain if antibiotics are recommended and how long they may be needed.