While less common in children than in adults, kidney stones can block the ureter (the tube that carries urine from the kidney to the bladder). Children with certain medical conditions or a family history of kidney stones may be more likely to develop them.

Conditions affecting the spinal cord, such as spina bifida, can affect the nerves that control the bladder. This may cause urine to back up into the kidneys.

Abnormal tissue in the urethra (the tube that carries urine out of the body) blocks urine from exiting the bladder.

Ureteral strictures are narrowed areas in the ureter, usually caused by inflammation, injury or congenital conditions. These narrowed areas can prevent normal urine flow out of the kidneys.

A UPJ obstruction is a blockage where the kidney connects to the ureter. This narrowed area prevents urine from flowing normally out of the kidney.

VUR causes urine to flow backward from the bladder up into one or both ureters and sometimes the kidneys. This backward flow causes one or both kidneys to swell.

A blood test can reveal your child's kidney function by measuring waste products in the blood. These tests help doctors understand how well the kidneys are filtering blood and whether hydronephrosis is affecting kidney health.

Your child's doctor will gently examine the abdomen to check for swelling, masses or tenderness. They will also look for signs of other birth defects that sometimes occur with hydronephrosis.

This test provides detailed information about how well each kidney is working and whether there is a blockage. Doctors give a small amount of radioactive material through an IV, and a special camera tracks how it moves through your child’s kidneys and bladder.

This test uses high-frequency sound waves to create pictures of your child's kidneys and urinary system. Ultrasound can show whether one or both kidneys are swollen and how severe the swelling is.

This urine test can detect signs of infection, blood or other problems in the urinary system. Children with hydronephrosis due to reflux are at higher risk for UTIs.

This bladder X-ray test checks for vesicoureteral reflux (backward flow of urine). A small catheter is placed in the bladder, and a special dye is used to fill the bladder. X-ray pictures are taken while your child urinates to see if urine flows backward into the ureters or kidneys. If your child is able to pee, this test can also assess the urethra.

If the swelling is not severe and kidney function is normal, your child's doctor may recommend careful monitoring with regular ultrasounds and kidney function tests. For some infants born with hydronephrosis, the condition resolves on its own as the urinary system matures.

Some children with hydronephrosis are at higher risk for UTIs. Your child's doctor may prescribe a low dose of antibiotics to take daily to help prevent infections. If your child develops a UTI, prompt antibiotic treatment can prevent kidney damage.

Pyeloplasty surgery can treat severe hydronephrosis caused by blockage where the ureter connects to the renal pelvis that is interfering with kidney function. During this surgery, the surgeon removes the narrow or blocked part of the ureter. The healthy part of the ureter is then reconnected to the kidney to allow normal urine flow.

If your child’s kidney is severely blocked or infected, doctors may place a ureteral stent (small tube) in the ureter to drain urine. A nephrostomy tube connects your kidney to the skin, bypassing your ureters. The tube may connect to a urine collection bag outside of your body instead. These are usually temporary solutions that protect your child’s kidneys before having surgery or other treatments.

Regular monitoring with ultrasounds and kidney function tests helps doctors detect any changes early. Even if your child seems healthy, these checkups are essential for detecting problems before they cause kidney damage.

Make sure your child drinks enough fluids throughout the day. Proper hydration helps the urinary system function well and may reduce the risk of kidney stones.

If your child is taking daily antibiotics to prevent infection, give them exactly as prescribed, even when your child feels well. Do not stop the medication without talking to your doctor first.

Children with hydronephrosis due to urine flowing back into the kidney are more prone to UTIs. Contact your doctor right away if your child has fever, painful urination, foul-smelling urine or abdominal pain.