Hydronephrosis

Hydronephrosis means distension of the kidney that is full of urine. It is a condition that can have various causes; sometimes the problem will resolve itself, but in other cases treatment will be needed to resolve the problem and prevent or relieve symptoms.

What is Hydronephrosis?

The term hydronephrosis refers to swelling in the kidneys as a result of fluid building up inside them. It can happen when the urine is unable to pass through the urinary tract (blockage) or flows back to the kidney from the bladder (known as reflux). It is very common in unborn babies. When it happens in the womb, the condition is known as antenatal hydronephrosis, and it is thought to affect about 1 in 100 babies.

Signs of Hydronephrosis

Since hydronephrosis frequently affects babies before they are born, it is often spotted during a routine pregnancy scan. The baby's kidneys can appear larger than normal on the ultrasound because of all the excess fluid they are holding.

Hydronephrosis can also be detected in babies or children. Generally, hydronephrosis does not cause symptoms but babies and children can develop urinary tract infections (UTIs), which might cause symptoms such as a fever, needing to urinate more often, or cloudy urine. Particularly when they are older, children can complain of pain in their back, side, or abdomen or have recurrent episodes of vomiting. You should see a doctor to find out what is causing these symptoms and obtain treatment if necessary.

Causes of Hydronephrosis

The most common causes of hydronephrosis are kidney obstruction (pelvi-ureteric junction obstruction -PUJO- or vesico-ureteric junction obstruction -VUJO-), Vesico-ureteric Reflux (VUR), Posterior Urethral Valves (PUV).

Antenatal hydronephrosis usually occurs because babies produce a lot more urine when they are in the womb than they do as newborns. The extra urine can make the kidney stretch and swell. However, there are other possible causes of hydronephrosis in babies and the problem can also occur in older children for several reasons. An infection could be preventing urine from flowing out of the kidneys properly or there might be a blockage in the urinary tract. Urine may be unable to leave the kidneys, or it could be pushed back into the kidneys through the urinary system. Sometimes the problem will affect both kidneys, but it is also possible for just one kidney to be affected while the other is still working normally.

Treatments for Hydronephrosis

Most cases of antenatally detected hydronephrosis remain stable or will go away by themselves. The kidneys are able to get rid of the excess urine and return to their normal size. If a baby is born with hydronephrosis then they will usually be checked after birth and be prescribed antibiotics to prevent an infection from developing.

If the problem does not resolve itself or there is another issue causing fluid to build up in the kidneys, then your child may need other treatments. Antibiotics can help reduce the risk of developing UTIs, but surgery may be necessary in the case of a blockage or reflux. A paediatric urologist can monitor your child's condition and advise on treatment options if action needs to be taken.