Your baby’s scan showed a swollen kidney.
Here’s what that means.
Hydronephrosis is one of the most common things found on pregnancy scans. Many cases get better on their own, and you don’t have to figure out the rest alone.
What is hydronephrosis?
Hydronephrosis means a kidney is swollen because urine isn’t draining out as easily as it should. Urine backs up and stretches the part of the kidney where it collects.
It’s a sign, not a full diagnosis. It tells your doctor that urine is backing up. The next step is finding out why.
How it’s usually found
On a routine pregnancy ultrasound, often in the second trimester
After birth, during tests for a urine infection
Sometimes by chance, during a scan for something else
What usually happens next
For many babies, mild swelling settles on its own as they grow. That’s why the most common next step is simply another scan, not treatment.
Your care team may:
Repeat the ultrasound after birth and over the first months
Check for urine infections
Order other tests if the swelling is larger or isn’t improving
Some children need medicine to prevent infections, and a smaller number need surgery to fix a blockage. Your team will explain what fits your child.
Questions to ask at your next appointment
How severe is the swelling, and is it one kidney or both?
What do you think is causing it?
When is the next scan?
What signs of infection should we watch for, and what should we do?
Who should we call if we’re worried between appointments?
Free resources for families
Short, plain-language guides made with families, free to download.
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This page is general information for families and is not medical advice. Always follow the advice of your child’s care team.
You're not alone.
Hydronephrosis is part of a group of conditions babies are born with that affect the kidneys and urinary tract. KidneyFuture supports people born with kidney and urinary tract differences — children and adults — and is working on therapies. Join us.
KidneyFuture is an official program of CAKUT Foundation Inc., a registered 501(c)(3) tax-exempt nonprofit organization (EIN: 39-3322233). We are dedicated to uniting families, clinicians, and researchers to transform outcomes for those born with kidney disease.
The information on this site is for general educational purposes only and is not medical advice. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition.
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