Hydronephrosis

Hydronephrosis is dilatation of part of the kidney. Generally, it’s due to the fact there is slow or sluggish drainage in part of the kidney, down to the ureter. The condition usually occurs in the womb and it is sometimes detected before a baby is born. However, hydronephrosis symptoms are sometimes only recognised during investigations into urinary problems that are performed after a baby is born.

Symptoms of Hydronephrosis

Hydronephrosis symptoms aren’t usually obvious, so the condition is usually detected during investigations that are being done for other reasons. When hydronephrosis occurs in the womb, it is often detected during the routine anomaly scan that is performed at around 20 weeks. Hydronephrosis symptoms can also be detected in babies after the birth if doctors are performing scans to investigate the causes of urinary symptoms.

Most children do not present with any signs or symptoms for unilateral hydronephrosis. Historically the most common symptom for hydronephrosis is in fact a urinary tract infection. The symptoms of urinary tract infection in the older child can consist of high temperature, pyrexia and dysuria (pain when voiding). There could be cloudy urine, blood in the urine and pain in the child’s side or their back. Younger babies will not necessarily present with clear symptoms and when they develop a urinary tract infection they can have high temperature, irritability and failure to thrive. The hydronephrosis can then be detected when an ultrasound scan is performed to investigate the causes of the urinary tract infections.

Presently a vast majority of children are diagnosed with hydronephrosis on fetal scans. At present, the 20 weeks scan can be useful for detecting hydronephrosis and this frequently means there may be further ultrasound scans required in pregnancy. This can occur at approximately 1 – 2% of all pregnancies. Hydronephrosis won’t usually cause any problems for the baby or the mother during pregnancy. However, additional monitoring may be recommended and treatment may be required after the baby is born.

In the occasion of unilateral hydronephrosis, the baby will require an ultrasound scan after the child is born. In certain situations, preventative antibiotics which will decrease the severity of infections will potentially be of benefit. In this situation your child will need some further investigations to see what is going on.

It is important for hydronephrosis symptoms to be investigated carefully in order to identify the cause of the problem. Untreated hydronephrosis could increase the risk of urinary tract infections and it might affect the functioning of the kidneys. The kidneys could be damaged if the problem is left untreated.

Causes of Hydronephrosis

Hydronephrosis happens when urine collects inside the kidneys. The kidney will then swell up. The increase in size can be detected on an ultrasound scan. Urine can build up inside the kidney if it isn’t able to make its way to the bladder or if it returns back up the ureter.

The kidneys are the organs that produce urine. Most people have two kidneys. Each kidney is connected to the bladder through a tube known as a ureter. The bladder collects the urine from the kidneys and stores it until it can be eliminated from the body by urination. The tube that carries urine from the bladder and out of the body is called the urethra. Valves normally prevent the urine from moving back up towards the kidneys.

Hydronephrosis can happen for a number of different reasons. In most cases, the problem will only affect one of the kidneys. This is known as unilateral hydronephrosis and it won’t usually cause serious issues as the unaffected kidney will still be able to function normally. However, in some cases, both kidneys can be affected. This can be more serious if the body is not able to eliminate waste by producing urine efficiently enough.

The most likely causes of hydronephrosis in babies are:

  • Blockages in the urinary tract. The blockage could be between the kidney and ureter, between the bladder and the ureter or in the urethra that leads out of the bladder.
  • Ureteric duplication, which happens when there are two ureters connecting one of the kidneys to the bladder. The lower end of one of these ureters is then likely to be blocked. This condition happens in about 1% of babies.
  • Multicystic dysplastic kidney (MCDK), which occurs when one of the kidneys fails to form correctly. The non-functioning kidney contains large numbers of cysts.
  • Vesico-ureteric reflux (VUR), which occurs when the valve where the ureter connects to the bladder doesn’t work properly. It isn’t able to stop urine from moving back up the ureter towards the kidney.

Surgery of Hydronephrosis

Hydronephrosis can be diagnosed using ultrasound scans to check for kidney enlargement and MAG3 scans to get more detailed pictures of the kidneys. MAG3 scans use a special isotope to check on the kidney’s structure and function. The isotope can be traced as it passes through the kidneys.

Depending on the ultrasound scan and MAG3 findings and their symptoms, some children will require surgery to improve drainage of their kidney. Usually procedure which is preformed is a pyeloplasty. This is an operation to remove the small narrowed area between the pelvis of the kidney and the ureter which is called the pelvi ureteric junction (PUJ). Once this is removed, two tubes are joined back together and a small stent is left internally. This is removed a number of months later.

If the hydronephrosis symptoms are caused by something other than a blockage in the ureter, then other approaches to treatment may be recommended. For example, if the condition is linked to a multicystic kidney, it may be sufficient to monitor the kidney to see if it shrinks by itself. However, if the kidney grows too large or starts raising the blood pressure, it may need to be removed. As long as the other kidney is functional, this should not cause any problems for the child’s health and wellbeing.

Antibiotics can also be prescribed to tackle urinary tract infections linked to hydronephrosis. However, the problem can return if the underlying cause is not addressed.

Hydronephrosis Post-Operation

Most children are able to go home the following day and some children will require two nights in hospital. In general, if the child is already on preventive antibiotics, they will remain on antibiotics until the stent is removed. A vast majority of children are very comfortable following the surgery. Once the stent is removed, the child will have a number of ultrasound scans and further MAG3 the following year to ensure their systems are working at the maximum capacity. After this, most children do not require further follow-up.

As long as hydronephrosis is detected and treated before the kidneys have been damaged, it won’t usually cause any long term health problems. If the condition is severe enough to damage the kidneys then they can become unable to function properly. Kidney failure can be very serious if both of the kidneys are affected so it is essential for hydronephrosis to be monitored and treated correctly.

Hydronephrosis FAQs

Hydronephrosis is very commonly seen on antenatal scans. A vast majority of people’s prenatal scans, one kidney can appear larger than normal. Normally this resolves in its own time and is due to alterations in either the flow or anatomy of the kidney.

Hydronephrosis can also be caused by stones or previous surgery and can be caused by other rare conditions.

A small number of children have a narrowing of the tube leading from the kidney. This is called a pelvi ureteric obstruction. There can also be a small kink and blockage of that area or there can be reflux, which allows urine to go back from the bladder to the kidney.

If hydronephrosis symptoms are detected in the womb then additional ultrasound scans are usually recommended to monitor the condition during the rest of the pregnancy. If the kidney grows too large, some of the fluid may need to be drained before the baby is born. However, in most cases the pregnancy and birth can proceed as normal, without any additional treatment.

The baby will continue to be monitored with ultrasound scans and other tests after the birth. These tests will also be recommended if hydronephrosis is detected after birth. The results will determine when and if further action needs to be taken. Surgery may be recommended if there is a blockage in the ureter or if the kidney has become very enlarged.

Monitoring is also recommended for at least a year after surgery to correct hydronephrosis. Ultrasound scans and MAG3 tests will be able to confirm that the treatment has been successful.

Most children do not present with any signs or symptoms for unilateral hydronephrosis. Historically the most common symptom for hydronephrosis is in fact a urinary tract infection. The symptoms of urinary tract infection in the older child can consist of high temperature, pyrexia and dysuria (pain when voiding). There could be cloudy urine, blood in the urine and pain in the child’s side or their back. Younger children will not necessarily present with clear symptoms and when they develop a urinary tract infection they can have high temperature, irritability and failure to thrive without any clear symptoms relating to the kidney. If your child experiences severe or recurring urinary tract infections then an ultrasound scan may be performed to check for blockages or other issues with the urinary system. The scan can then reveal hydronephrosis symptoms such as an enlarged kidney.

Presently a vast majority of children are diagnosed with hydronephrosis on fetal scans. At present, the 20 weeks scan can be useful for detecting hydronephrosis and this frequently means there may be further ultrasound scans required in pregnancy. This can occur at approximately 1 – 2% of all pregnancies. However, hydronephrosis symptoms can also be detected after the baby is born. This usually happens when ultrasound scans are performed to check on the kidneys due to recurring urinary tract infections or other issues.

In the occasion of unilateral hydronephrosis, they will require an ultrasound scan after the child is born. In certain situations preventable antibiotics which will decrease the severity of infections will potentially be of benefit.

In this situation your child will need some further investigations to see what is going on. They will require at least an ultrasound scan of the kidneys and a micturating cystourethrogram (MCUG). They will also require a nuclear medicine which is called a DMSA scan which will be able to determine the presence of scars.

The vast majority of children will not require a MCUG and merely require an ultrasound scan. Some children require both an ultrasound scan and a nuclear medicine test.

Depending on the ultrasound scan and MAG3 findings and their symptoms, some children will require surgery to improve drainage of their kidney. Usually procedure which is preformed is a pyeloplasty. This is an operation to remove the small narrowed area between the pelvis of the kidney and the ureter where the pelvi ureteric junction is. Once this is removed, two tubes are joined back together and a small stent is left internally. This is removed a number of months later.

Most children are able to go home the following day and some children will require two nights in hospital. In general, if the child is already on preventive antibiotics, they will remain on antibiotics until the stent is removed. A vast majority of children are very comfortable following the surgery. More details are given at that stage.

Once the stent is removed, the child will have a number of ultrasound scans and further MAG3 the following year to ensure their systems are working at the maximum capacity. After this most children do not require further follow-up.

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