Main > Newborn > Common Newborn Problems > Prenatal Hydronephrosis

Having 'fluid on the kidneys' before birth is referred to as prenatal hydronephrosis. It is the most common abnormality found on prenatal ultrasound and is found in almost 1.4% of fetuses.

Related Topics Vesicoureteral Reflux UTI's

Causes of prenatal hydronephrosis can include a ureteropelvic junction (UPJ) obstruction (most common), vesicoureteral reflux, megaureter, or posterior urethral valves (found in males who may also have a dilated bladder on prental ultrasound).

More reassuring though, is that 50% of babies who had prenatal hydronephrosis have no evidence of hydronephrosis after being born.

An important part of the evaluation of a baby with prenatal hydronephrosis is if there is a normal amount of amniotic fluid. If there isn't, and you have decreased fluid, then that could be a sign that the babies kidneys aren't working properly and that might be an indication to deliver at a tertiary care center.

After delivery, your child will likely have a renal ultrasound and voiding cystourethrogram (VCUG) at some point on an outpatient basis. They are generally done at least 2-3 days after birth, but may then be done anytime during the first 4-6 weeks of life, unless the dilation is severe. The postnatal renal ultrasound will again look for hydronephrosis, while the VCUG will check for reflux. Until the tests are done, your baby will likely be placed on antibiotics (usually Amoxicillin) to prevent urinary tract infections.

Depending on the initial test results, further testing might also be needed, including a renal scan.

The postnatal evaluation of children with prenatal hydronephrosis is actually a little controversial. Some doctors recommend just doing a postnatal ultrasound, and nothing further if it is normal and a VCUG only if hydroneprhosis is still present. Other doctors think that all of these children should have a VCUG, even if the initial postnatal ultrasound is normal, since these children could still have reflux.

I generally place otherwise well newborns with prenatally diagnosed hydronephrosis on Amoxicillin and do both a renal sonogram and a VCUG as an outpatient. If the tests are abnormal, then I generally refer those patients to a Pediatric Urologist.

If you would feel more comfortable, you could also arrange an evaluation with a Pediatric Urologist either before or after the baby is born.

Prenatal Hydronephrosis Internet Links:

• Detecting Kidney and Urinary Tract Abnormalities Before Birth
  
  
• Pediatric Urology / Prenatal Hydronephrosis
  
  
• Questions and Answers Pediatric Urology: Prenatal issues
  
  
• Prenatal Ultrasound Uncovers More Urinary Tract Abnormalities
  
  
• Find a Pediatric Urologist: Look in the 'Membership by state/territory' to find a specialist in your area and then look for their name in the 'Active Membership' to find contact info. Specialists in Pediatric Urology take care of children with genital, bladder and urinary problems, including reflux and voiding dysfunction.

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Important disclaimer: The information on keepkidshealthy.com is for educational purposes only and should not be considered to be medical advice. It is not meant to replace the advice of the physician who cares for your child. All medical advice and information should be considered to be incomplete without a physical exam, which is not possible without a visit to your doctor.