Hydronephrosis

Page last reviewed: 13/07/2011

Hydronephrosis is a condition where one or both kidneys become stretched and swollen as a result of a build-up of urine inside the kidney(s).

The most common symptom of hydronephrosis is a severe pain that develops in your back or side, between your ribs and hip

Causes of hydronephrosis

There are two main causes of hydronephrosis. It can occur when one of the following happens:

  • There is a blockage somewhere in your urinary tract (see box, left), which is the most common cause.
  • Something disrupts the normal workings of your bladder which causes urine to flow back from the bladder and into the kidney(s).

 

Hydronephrosis can occur in pregnant women and in cases where cancers develop inside the urinary tract, such as such as or in the cervix . The cervix is the neck of the womb.

In men, hydronephrosis can sometimes occur in those who have a swollen prostate gland or prostate cancer. Kidney stones are also a common cause of hydronephrosis in both men and women.

For most cases of hydronephrosis, surgery is required to drain urine away from the kidneys and remove any blockage.

Antenatal hydronephrosis

Hydronephrosis is increasingly being found in unborn babies during routine ultrasound scans which are carried out during pregnancy. This type of hydronephrosis is known as antenatal hydronephrosis.

The most common cause of antenatal hydronephrosis is thought to be underdevelopment of the urinary tract, which leads to urine becoming trapped inside a kidney.

As a parent, it can initially be worrying to learn that your baby has a problem with their kidneys. However, most cases of antenatal hydronephrosis are not serious and should not affect the outcome of your pregnancy.

About four out of five cases of antenatal hydronephrosis will resolve on their own before, or shortly after, birth. The remaining cases may require treatment with antibiotics to prevent kidney infections occurring, as bacteria can breed in the trapped urine. In some cases, surgery may be needed.

How common is hydronephrosis?

It is estimated each year that around 1 in every 300 people has one kidney that is affected by hydronephrosis (unilateral hydronephrosis), while 1 in every 600 people have both affected (bilateral hydronephrosis).

Antenatal hydronephrosis is one of the most common abnormalities detected during antenatal scanning. It is estimated that about 1 in every 100 pregnancies is affected by antenatal hydronephrosis.

Outlook

The outlook for hydronephrosis is generally good as long as the condition is diagnosed and treated promptly. If left untreated for several weeks, the kidney(s) may become scarred, which could lead to kidney failure (loss of normal kidney function).

Bladder
The bladder is a small organ near the pelvis that holds urine until it is ready to be passed from the body.
Kidneys
Kidneys are a pair of bean-shaped organs located at the back of the abdomen. They remove waste and extra fluid from the blood and pass them out of the body as urine.
Ultrasound
Ultrasound scans are a way of producing pictures of the inside of the body using soundwaves.

The urinary tract

The urinary tract is made up of:

  • the kidneys – they extract waste materials from the blood and convert it into urine
  • the ureters – they are the tubes that run from the kidney to the bladder
  • the bladder – a "balloon-shaped" organ that is used to store urine
  • the urethra – this is the tube that runs from the bladder through the penis (in males) or vulva (in females), through which urine passes

Page last reviewed: 13/07/2011

If you have hydronephrosis, your symptoms will depend on whether the urine blockage occurred quickly or gradually.

If the blockage forms quickly (acute hydronephrosis) - for example, as a result of a kidney stone, your symptoms will develop over the course of a few hours. If the blockage develops gradually, over a period of weeks or months (chronic hydronephrosis), you may experience few or no symptoms.

The type of symptoms that you will experience will also depend on where the problem is and the length of time that the flow of urine remains blocked. How severe your symptoms are will depend on the extent of the urine blockage and how much your kidney has been stretched.

Acute hydronephrosis

The most common symptom of acute hydronephrosis is a severe pain in your back or side, between your ribs and hip. The pain will be on the side of the affected kidney or on both sides if both kidneys are affected. In some cases, the pain may travel towards the testicles (in men) or vagina (in women).

The pain usually comes and goes and is often worse when drinking fluid. As well as pain, you may also experience nausea and vomiting.

If the urine inside your kidney becomes infected, you will also have symptoms of a kidney infection, such as:

  • a high temperature (fever) of 38C (100.4F) or above
  • uncontrollable shivering
  • diarrhoea

If the blockage of urine has been caused by a kidney stone, you may notice the presence of blood in your urine. In severe cases of hydronephrosis, one or both of your kidneys may be noticeably swollen to the touch.

Chronic hydronephrosis

If your hydronephrosis is caused by a blockage that develops gradually over a long period of time, you may experience:

  • the same symptoms as acute hydronephrosis (see above)
  • no symptoms at all
  • a dull ache in your side that comes and goes

You might also urinate less often than you used to.

When to seek medical advice

Always contact your GP if you:

  • develop a severe and persistent pain
  • have symptoms, such as a high temperature, which suggest that you may have an infection
  • notice a uncharacteristic change in how often you urinate
Aching
An ache is a constant dull pain in a part of the body.
Acute
Acute means occuring suddenly or over a short period of time.  
Fever
A high temperature, also known as a fever, is when someone's body temperature goes above the normal 37°C (98.6°F).  
Kidneys
Kidneys are a pair of bean-shaped organs located at the back of the abdomen, which remove waste and extra fluid from the blood and pass them out of the body as urine.
Nausea
Nausea is when you feel like you are going to be sick.
Pain
Pain is an unpleasant physical or emotional feeling that your body produces as a warning sign that it has been damaged.
Swelling
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Urethra
The urethra is a tube that carries urine from the bladder to the outside of the body.
Vomiting
Vomiting is when you bring up the contents of your stomach through your mouth.

Page last reviewed: 13/07/2011

The two most common reasons that hydronephrosis occurs is either when there is a blockage inside the urinary tract or something disrupts the normal workings of the urinary tract, such as the bladder.

Common causes

In men, the two most common causes of hydronephrosis are:

  • non-cancerous swelling of the prostate gland (benign prostatic hyperplasia)
  • prostate cancer 

Both conditions can place pressure on the ureters, which can block the flow of urine. The ureters are the tubes that run from your kidneys to your bladder.

In women, common causes of hydronephrosis include:

  • pregnancy - during pregnancy the enlarged womb (uterus) can sometimes place pressure on the ureters
  • cancers that develop inside the urinary tract, such as bladder cancer or kidney cancer
  • cancers that develop inside the reproductive system, such as cervical cancer, ovarian cancer or cancer of the womb

Abnormal tissue growth associated with cancer can place pressure on the ureter or disrupt the workings of the bladder.

Kidney stones are another common cause of hydronephrosis in both men and women. Kidney stones are small stones that are made up of various substances that form in the kidneys. They can sometimes travel out of a kidney and into the ureters where they can block the flow of urine.

Other causes

Other less common causes of hydronephrosis include:

  • a blood clot (embolism) - which develops inside the urinary tract
  • endometriosis - a condition where tissue that should only grow inside the womb starts to grow outside of the womb; this abnormal growth can sometimes disrupt the urinary tract
  • tuberculosis - a bacterial infection that usually develops inside the lungs but in some cases can also spread to the bladder
  • damage to the nerves that control the bladder (neurogenic bladder)
  • ovarian cysts - fluid-filled sacs that develop inside the ovaries; larger ovaries can sometimes place the bladder or ureter under pressure
  • narrowing of the ureter as a result of injury, infection or surgery

Antenatal hydronephrosis

Most cases of antenatal hydronephrosis are thought to be caused by the ureters not developing as quickly as they should. When the ureters first develop they are solid cords of tissue that later transform into tubes with a hollow passageway. A delay in this development can cause temporary hydronephrosis.

Other causes of antenatal hydronephrosis include:

  • a blockage - at the point where the ureters join the kidneys; the blockage can be due to a birth defect, although in many cases there is no obvious cause
  • primary vesicoureteral reflux - this is a childhood condition where the valve that controls the flow of urine between the bladder and the ureter does not function properly, allowing urine to flow back up to the kidneys; most children will grow out of primary vesicoureteral reflux

Page last reviewed: 13/07/2011

Ultrasound scan

An ultrasound scan is the usual method of diagnosing hydronephrosis. This type of scan uses sound waves to create a picture of the inside of your kidneys. If your kidneys are swollen, this should show up clearly on your ultrasound scan.

Further tests

It is not usually possible to determine the cause of hydronephrosis from an ultrasound scan. Therefore, it may be recommended that you have a number of additional tests to help determine the cause. These may include:

  • blood tests - which can be used to check for infection
  • urine tests - which can be used to check for infection as well as traces of blood (if blood is found it could be caused by a kidney stone)
  • intravenous urography - this is an X-ray of your kidneys that is taken after a special dye has been injected into your bloodstream; the dye highlights the flow of urine through your urinary tract, which can be useful for identifying any blockages
  • computerised tomography (CT) scan - this is similar to an X-ray but it uses multiple images and a computer to build up a three-dimensional picture of the inside of your body
Intravenous
Intravenous (IV) means the injection of blood, drugs or fluids into the bloodstream through a vein.
Kidney
Kidneys are a pair of bean-shaped organs located at the back of the abdomen, which remove waste and extra fluid from the blood and pass them out of the body as urine.
MRI
MRI stands for magnetic resonance imaging. It is the use of magnets and radiowaves to take detailed pictures of inside the body.
Swelling
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Ultrasound scan
Ultrasound scans are a way of producing pictures of inside the body using soundwaves.
Urethra
The urethra is a tube that carries urine from the bladder to the outside of the body.
Urine test
Urinalysis/UA is when a urine sample is tested, commonly to check for any signs of infection, or protein or sugar levels.

Antenatal hydronephrosis

Hydronephrosis may be diagnosed in your baby during pregnancy, during a routine ultrasound scan.

Your baby will be monitored with ultrasound scans to check it is growing normally and the kidneys are not getting too large.

Page last reviewed: 13/07/2011

Your treatment plan

If you have hydronephrosis, your treatment will depend on what is causing the condition and how severe the urinary blockage is. The aim of the treatment is to:

  • remove the build-up of urine and relieve the pressure on your kidney(s)
  • prevent permanent kidney damage
  • treat the underlying cause of hydronephrosis

Most cases of hydronephrosis will need to be treated surgically using a combination of techniques (see below).

The timing of your treatment will depend on whether or not you have the symptoms of infection. If you do, there is a risk that the infection could spread into your blood. This is known as blood poisoning or sepsis and it can be very serious. In such circumstances, it may be recommended that surgery is carried out on the same day that the diagnosis is confirmed.

Immediate surgery may also be recommended if both of your kidneys are affected or if you have symptoms including severe pain, vomiting and nausea that can't be relieved with medication.

If you do not have the symptoms mentioned above, it may be considered safe to delay surgery for a few days.

Draining the urine

The first stage in treating hydronephrosis is to drain the urine out of your kidneys. This will help to ease your pain and prevent damage to your kidneys.

A thin tube called a catheter may be inserted into your bladder through your urethra (the tube through which urine is passed out of the body), or directly into your kidney through a small incision in your skin. This will allow urine to flow and relieve the pressure on the kidney.

Treating the underlying cause

Once the pressure on your kidney has been relieved, the cause of the build-up of urine must be treated. This will usually involve removing a blockage.

Blockages of the ureter (a common cause of hydronephrosis) can be treated using a type of surgery called ureteral stenting. It involves placing a small tube inside the ureter which is used to bypass the site of a blockage. The stent can be passed into the ureter (the tube that passes from the kidney to the bladder) without making major incisions in your body.

Once the urine has been drained and the ureter unblocked, the underlying cause will need to be treated to prevent hydronephrosis returning. Some possible causes and their treatments are described below.

  • Kidney stones - these can be broken up using sound waves or lasers
  • A swollen prostate - this can be treated with medication or, less commonly, surgery to remove some or all of the prostate
  • Cancers - some cancers, such as cervical cancer or prostate cancer, are associated with hydronephrosis and can be treated using a combination of chemotherapy, radiotherapy and surgery to remove the diseased tissue.

If a woman's pregnancy is causing hydronephrosis, there is little that can be done to cure it other than waiting for the pregnancy to take its natural course. However, the condition can be managed by regularly draining the kidneys with a catheter throughout the pregnancy to prevent kidney damage.

Antenatal hydronephrosis

Most cases of antenatal hydronephrosis do not require any treatment because they usually resolve on their own before birth. However, frequent ultrasound scans will probably be recommended so that the extent of the swelling of the kidneys can be regularly assessed.

If hydronephrosis is present after birth, the recommended treatment will depend on the underlying cause. If your child's hydronephrosis is due to primary vesicoureteral reflux (where the valve in their bladder does not work properly) then no immediate treatment will probably be needed. This is because most children will grow out of primary vesicoureteral reflux as they get older.

However, the urine inside their kidneys can make them more vulnerable to infection, so regular doses of antibiotic tablets may be recommended as a precaution.

Your child will need regular urine tests and ultrasound scans to monitor how they are responding to antibiotic treatment and to assess the swelling inside their kidney(s).

Surgery will be considered if your child does not grow out of primary vesicoureteral reflux, or if their hydronephrosis is severe enough to pose a threat to their health or adversely affect their quality of life.

If surgery is recommended, the surgeon can inject substances around the malfunctioning bladder valve, which should help to improve its functioning. Keyhole (laparoscopic) surgery is usually used where only small cuts are made in the skin and tiny instruments are passed through them. The advantage of this type of surgery is that it causes minimal scarring and has a quicker recovery time than traditional open surgery.

If your child's hydronephrosis is caused by a blockage, this will need to be treated surgically in the same way as it is in adults (see above).

Acute
Acute means occuring suddenly or over a short period of time.
Bladder
The bladder is a small organ near the pelvis that holds urine until it is ready to be passed from the body.
Bypass
A bypass is when the flow of blood or other fluid is redirected, permanently because of a blockage in the body, or temporarily during an operation.
Catheter
A catheter is a thin, hollow tube usually made of rubber that is placed into the bladder to inject or remove fluid.
Incision
An incision is a cut made in the body with a surgical instrument during an operation.
Kidneys
Kidneys are a pair of bean-shaped organs located at the back of the abdomen, which remove waste and extra fluid from the blood and pass them out of the body as urine.
Ultrasound scans
Ultrasound scans are a way of producing pictures of inside the body using sound waves.
Womb
The uterus (also known as the womb) is a hollow, pear-shaped organ in a woman where a baby grows during pregnancy.

Page last reviewed: 13/07/2011

Kidney failure

In cases of severe hydronephrosis that are not treated promptly, scarring of the kidney can occur. In the most serious of cases, this can lead to kidney failure (loss of normal kidney function).

Most people can function normally with just one working kidney, so the failure of a single kidney will probably not significantly affect your health or lifestyle. However, if the failed kidney has been affected by an underlying condition, such as cancer or infection, surgically removing the kidney may be recommended.

If both kidneys fail, it will have a major impact on your health. Your kidneys perform a number of important functions, such as filtering waste products from your blood and helping to regulate blood pressure. Therefore, kidney failure can cause a wide range of symptoms, such as:

  • tiredness
  • swollen ankles, feet or hands (due to water retention)
  • shortness of breath
  • feeling sick
  • blood in your urine

There are two main treatment options for kidney failure. They are:

  • kidney transplant - where a donated kidney that is usually provided by a living donor is surgically transplanted into your body
  • dialysis - where a machine is used to replicate the most important function of the kidneys, which is filtering your blood
Bladder
The bladder is a small organ near the pelvis that holds urine until it is ready to be passed from the body.
Kidney
Kidneys are a pair of bean-shaped organs located at the back of the abdomen that remove waste and extra fluid from the blood and pass them out of the body as urine.
Pain
Pain is an unpleasant physical or emotional feeling that your body produces as a warning sign that it has been damaged.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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