How does the urinary system work?
The urinary system consists of the kidneys, the bladder and ureters. The kidneys filter the blood to remove waste products and form urine. The urine flows from the kidneys down through the ureters to the bladder. From here it passes through another tube called the urethra to the outside when urinating.
The ureters tunnel through the wall of the bladder at an angle to form a flap that acts as a valve. There is also a ring of muscle (sphincter) at the junction of the bladder and the urethra that stops urine leaking out in between episodes of urination. When passing urine, the muscles of the bladder wall squeeze the urine out of the bladder, at the same time as the muscles in the sphincter need to relax to let the urine flow down the urethra.
The valves between the ureters and the bladder prevent urine flowing backwards into the ureters, so that all the urine in the bladder is passed in one go, as the urine cannot travel anywhere else. As the urine leaves the bladder at a high pressure, the valves stop this high pressure being passed on to the kidneys.
What is hydronephrosis?
Hydronephrosis is a condition that can occur in the womb, where a baby’s kidneys fill up with urine and become larger. This can happen for various reasons. Hydronephrosis can also occur in adults, but the cause and treatment modalities are different from that of a child.
What are the symptoms of hydronephrosis?
Even if hydronephrosis is diagnosed before birth, this should not cause any symptoms in the mother and should not alter her antenatal care, other than possibly having a few more scans. Hydronephrosis does not usually cause a baby any problems before birth, but he or she may need close monitoring and assessment after birth to discover what is causing the hydronephrosis and keep an eye on the condition.
How is hydronephrosis diagnosed?
It is often diagnosed before a baby is born, as the enlarged kidneys can be seen on an ultrasound scan. Hydronephrosis can also be diagnosed after the baby is born using ultrasound scans.
What causes hydronephrosis?
There are many causes of hydronephrosis, including:
A blockage, which can occur between the kidney and the ureter (pelviureteric junction or PUJ), between the bladder and the ureter (vesicoureteric junction or VUJ) or in the urethra (posterior urethral valve).
How common is the condition?
About 1 in every 300 people has one kidney affected by hydronephrosis. About 1 in every 600 people have both kidneys affected by hydronephrosis.
How can hydronephrosis be treated?
If the hydronephrosis is diagnosed during pregnancy, early treatment will consist of monitoring with ultrasound, to check that the baby is growing normally and the kidneys are not getting too large. The baby will usually be born by a routine delivery.
After the baby is born, the hydronephrosis will be monitored using ultrasound scans and other tests. The overall treatment for hydronephrosis depends on what is causing it:
- If the cause is VUR, the child will probably be treated using antibiotics. Details can be obtained on the information on vesicoureteric reflux.
- If the cause is a blockage, the treatment will depend on the degree of the blockage, the effect it is causing on the functioning of the kidneys or symptoms it is producing i.e. pain, urinary tract infections etc. In severe cases surgery may be necessary to clear the blockage. Many children with mild or moderate degrees of obstruction, regular follow up with close monitoring may be necessary. The decision of treatment however varies from child to child. Operation done for hydronephrosis to clear the blockage between the kidney and ureter is called a ‘pyeloplasty’.
What is the future for children with hydronephrosis?
If the cause of the hydronephrosis is an obstruction and this is removed, your child’s kidneys will be able to work properly. If the cause of the hydronephrosis is VUR that is not too severe, your child’s kidneys are also likely to work properly. If the cause of the hydronephrosis is severe VUR, the outlook may be less good. Your child may need an operation to correct the reflux and his or her kidneys may be damaged. However, the earlier the hydronephrosis is discovered, the better the outcome for your child.
What is a pyeloplasty and why is it needed?
A pyeloplasty is an operation to remove a blockage in one of the ureters.
The blockage in one of the ureters is stopping urine flowing easily from the kidney into the bladder. The blockage is usually present from birth, but occasionally may appear later. If the ureter remains blocked, the kidney could become swollen and damaged. Sometimes, the blockage is caused by blood vessels getting in the way of the ureter. In this case, they will be moved and secured away from the ureter during the operation, but not removed.
What does the operation involve?
The operation involves locating the blockage in the ureter, remove the affected section and joining the cut ends of the ureter again. Details regarding the same will be explained in further details by the doctor.
