Hydronephrosis is a medical condition affecting your child’s kidneys. With efficient diagnosis and treatment, it is possible to successfully manage hydronephrosis. However, if left untreated, in some cases hydronephrosis can lead to kidney scarring and potentially loss of kidney function (kidney failure).

At Evelina London Children’s Hospital, our paediatric urology specialists diagnose hydronephrosis promptly, so your child can receive treatment fast.

What is hydronephrosis?

Hydronephrosis affects one or both kidneys and occurs when they become stretched or swollen due to a urine build-up inside it. This condition can affect people at any age. It is commonly picked up in unborn babies — antenatal hydronephrosis — during ultrasound scans in pregnancy.

Hydronephrosis does not cause long-term health problems if doctors treat it quickly but can increase your child’s risk of developing urinary tract infections (UTIs).

Hydronephrosis symptoms

The majority of hydronephrosis cases in children are symptomless, however in some cases it can present as:

  • urinary tract infection
  • a weak stream of urine
  • pain in the back or side (this can be sudden or a dull ache that comes and goes)
  • abdominal lump
  • blood in the urine

If your child experiences these symptoms, they may need an ultrasound scan to check their kidney health.

What causes hydronephrosis?

A urinary tract blockage typically causes hydronephrosis. Your child’s urinary tract includes their kidneys, bladder, ureters (the tubes connecting the kidney to the bladder) and urethra (the tube passing urine out of their body).

However, urine cannot drain from their kidneys if the urinary tract becomes blocked. The resulting build-up of urine in your child’s kidneys can cause them to swell.

The causes of hydronephrosis are varied, but the most common are the following:

  • narrowing of the junction between kidney and ureters
  • urinary reflux (urine going backward from the bladder to the kidneys)
  • kidney stones
  • neurogenic bladder (damage to the nerves controlling the bladder)

Antenatal hydronephrosis

Antenatal hydronephrosis generally doesn’t cause visible symptoms before or after your baby’s birth, but it is essential to clarify the situation with a medical professional.

If you believe your baby does have symptoms, such as a high fever, not caused by other conditions it is essential to seek medical attention for further investigations.

Our expert paediatric urologist works together with our fetal medicine specialists to accurately diagnose and treat your baby.

The cause of hydronephrosis in babies is unclear. Experts believe an increase in your baby’s urine production and the effect of maternal hormones during the later stages of pregnancy may cause it (physiological hydronephrosis).

When a baby is born, their kidneys will function correctly and the condition should resolve within a few months. However, in some cases there could be an underlying cause so it is worth speaking with our children’s urology team.

How is hydronephrosis diagnosed?

Once one of our specialists confirms hydronephrosis, your child may need further testing to determine the underlying cause.

These tests can include:

  • ultrasound scan
  • blood and urine tests
  • nuclear medicine test (like MAG-3 and DMSA scans)
  • micturating cystogram (MUCG)

Hydronephrosis treatment

The majority of hydronephrosis cases resolve on their own.

For those that do require treatment, our paediatric urologist will discuss with you the different types of surgical intervention options depending on the site of the blockage.

While your child is being investigated to understand the cause, they will be put on low dose preventative antibiotics to avoid infections.

If the blockage is at the junction of the kidney and ureter it could be corrected by a surgery called pyeloplasty which is commonly performed via keyhole technique (laparoscopy).

If the blockage is in the urethra or because of urinary reflux, it could be corrected by inserting a camera through the urethra (cystoscopy) to clear it.

If your child’s kidney is severely affected and causing infections, it might be better to have it removed. Removal should not significantly impact their overall health and they can function as usual with just one kidney.

Hydronephrosis complications

One of the most common complications of hydronephrosis is a UTI because the interrupted urine flow increases the risk of infection.

Another complication of severe hydronephrosis, if it involves both kidneys, is kidney damage and kidney failure. However, it is possible to avoid permanent kidney damage and kidney failure with prompt treatment.

Discover our children's urology experts

At Evelina London, as part of Guy’s and St Thomas’ Specialist Care, we provide the vital treatment your child needs. Our highly experienced urology and fetal medicine teams work together to ensure an accurate diagnosis and speedy treatment.