Kidney biopsy

A kidney biopsy is a procedure to remove a very small piece of kidney tissue so it can be examined under a microscope.

A kidney biopsy is usually carried out to determine or confirm a diagnosis. It can also be useful in assessing how the kidneys are responding to treatment.

It may become necessary when blood and urine tests, ultrasound scans and other radiology imaging have not been able to find the cause of your child’s kidney problem or whether specific treatment is needed.

Some of the problems that might need a kidney biopsy include recurrent episodes when blood can be seen in the urine, the presence of large amounts of protein in the urine and when kidney function has deteriorated rapidly and the cause is not known. In children who have had kidney transplants, it can identify why the transplanted kidney is not working well and what treatment is needed.

You will already have received information about how to prepare your child for the procedure in your admission letter. You may need to come to GOSH before the procedure so that your child can have a pre-admission assessment to check that they are well enough. This appointment may involve taking blood samples and other tests.

We need to be sure that your child’s blood clots properly so we will take a small blood sample for testing. This is because healing after the procedure relies on blood clotting. We also check your child’s blood group so that if we need to give your child blood, we can organize this.

Your child will need to be admitted to a bed on a ward in the hospital. We will discuss with you whether you need to come in the night before or very early on the day of the biopsy. The person bringing your child to the procedure should have ‘parental responsibility’ for them. Parental responsibility refers to the individual who has legal rights, responsibilities, duties, power and authority to make decisions for a child. If the person bringing your child does not have parental responsibility, we may have to cancel the procedure.

An anaesthetist will visit to talk to you about your child’s anaesthetic. The specialist performing the procedure will explain the procedure in more detail, discuss any questions you may have and ask you to sign a consent form giving permission for your child to have the kidney biopsy. If your child has any medical problems, please tell the specialists.

The doctor will also discuss whether your child needs a general anaesthetic for the procedure. Older children and young people may prefer to be awake and use a gas and air mixture called Entonox® to help with anxiety and pain relief.

Most kidney biopsies do not involve the use of X-rays. If we do need to use them, legally, we are obliged to ask anyone over the age of 12 whether there is any chance they might be pregnant, and we will also ask for the first date of their last period (if started). This is to protect babies in the womb from receiving unnecessary radiation.

You and your child will then be brought to the Interventional Radiology (IR) suite within the X-ray department for the procedure. Your child can walk or wheel to the department or you can carry them, but they will return to the ward on a bed. If the procedure is under local or Entonox then you will be able to stay with them during the procedure.

You will already have received information about how to prepare your child for the procedure in your admission letter. You may need to come to GOSH before the procedure so that your child can have a pre-admission assessment to check that they are well enough. This appointment may involve taking blood samples and other tests.

This test can be performed under local, Entonox or general anaesthetic. Your admission letter will specify which type you need to prepare for. For local anaesthetic there is no fasting required. For Entonox fasting is required for one hour before the procedure – this means no food or water. For general anaesthetic please follow the below instructions.

Your child needs to be fasted for the procedure for the general anaesthetic. If your child takes regular medication, please speak to your child’s team about when to stop these before the procedure.

As a general rule:

Food and milk:

Water:

It is equally important to keep giving your child food and drink until those times to ensure they remain well-hydrated and get adequate nutrition. This may involve waking your child in the night to give them a drink which we recommend.

Please follow these instructions carefully, otherwise your child’s procedure may be delayed or even cancelled.

Your child will lay on their left side if their own kidney (native kidney) is being biopsied. If the biopsy is on a transplanted kidney, your child will lie on their back, as this makes it easier to feel the transplanted kidney.

The exact position of the kidney, whether native or transplanted, is confirmed using an ultrasound scan, which also identifies the best place to take the biopsy. This is usually at the lower and outer part of the kidney.

Local anaesthetic is injected under the skin at the biopsy site. When this is numb, the needle is inserted more deeply to numb the path between the skin and the kidney. A tiny cut is made in the skin to allow the biopsy needle to enter more easily. This cut is 2 to 3mm long and is so small that it does not need a stitch afterwards.

When the radiologist had identified the right position for the biopsy, they will insert the needle while your child holds their and then quickly withdraw it again. The process may need to be repeated if the sample if small.

The biopsy needle has a hollow centre, and when it is removed, it brings a very fine core of kidney with it. This is about the size of a piece of thick cotton and is approximately 1 to 2cm long. This tiny piece of kidney will take away between ten and 50 glomeruli, which are the little filtering units within the kidney. This will not affect kidney function as each kidney contains about one million glomeruli.

The sample of kidney tissue is given to the histopathology technician who looks at it under the microscope to make sure the sample is adequate. If the sample is too small, a second will be taken during the same procedure. If the sample is suitable, the technician will take it for processing.

The incision site will be closed by STERIStrips, which are like strong sticky plasters, and then covered with a dressing. The area usually bleeds slightly straight after the procedure, but this will stop when pressure is applied to the site. Your child will then return to the ward where they need very frequent observations of their heart rate, breathing and blood pressure. This is because very rarely a child can bleed after a kidney biopsy as we rely on natural blood clotting for it to heal. For this reason, we need your child to lie still for at least four hours afterwards.

If you child will be having the procedure under general anaesthetic, every anaesthetic carries a risk, but this is extremely small.

Some children may get a little bit of pain over the biopsy site, but this is not usually serious. Paracetamol is usually enough to help this.

Another potential complication is bleeding so that your child’s urine may look red. This is because the kidney has a lot of blood flowing through it all the time. The nurse will check your child’s blood pressure and pulse so that if any bleeding occurs, it can be picked up quickly. Very rarely it is necessary to give a blood transfusion, and every more rarely, it has been reported that kidneys have stopped working due to bleeding.

Another rare complication is that if the blood causes clots in the urine, a bladder catheter may be needed if the clots are stopping urine being passed. Another complication is the creation of a join between a small artery and a small vein, called a fistula, which can very occasionally cause bleeding and blood pressure problems.

The procedure may involve the use of X-rays. The levels that are used are low dose and therefore low risk. If you have any concerns regarding the use of radiation, please discuss this with the person performing your procedure beforehand.

We will usually let you and your child go home about six hours after the biopsy if:

• Their blood pressure, pulse and breathing remain satisfactory.
• The biopsy site looks fine.
• They have passed urine (peed) that is not heavily blood stained on two occasions.

However, if the biopsy took place late into the afternoon, your child may need to stay overnight.

• Keep the dressing dry and in place for a day or two after the procedure. This helps the biopsy site to heal and reduces the risk of scarring. The dressing can then be removed. The STERI-strips used to seal the wound may fall off their own accord – otherwise, you can gently peel them off three days after the biopsy.
• Your child may feel uncomfortable for a couple of days afterwards and may experience a dull ache in the area where the biopsy was taken. It is fine to give your child paracetamol – according to packet instructions – unless you have been advised otherwise.
• Your child’s urine may look slightly pink afterwards due to a small amount of bleeding. This will usually settle down within 72 hours.
• When you get home your child should take it easy and not run around or ride a bike for two weeks. We advise that they stay off school for two days after the biopsy. Your child should avoid horse riding and contact sports such as rugby for the next four weeks to allow the kidney to heal properly.

You should call the hospital (or go to A&E out of hours) if:

• Your child has blood-stained urine.
• The biopsy site is still painful more than three days after the biopsy and normal pain relief is not helping.
• The biopsy site is oozing or bleeding.
• Your child has a temperature of 38⁰C or higher.

You can call the ward by calling the GOSH switchboard asking for the ward your child was discharged from.

Telephone: 020 7405 9200

If you are unable to get through, please call NHS111 by dialling 111.

The biopsy is processed in three different ways. First, we look at it under a microscope. This may give us some information within a day or two.

We then do special stains on the sample, which takes a bit longer, and electron microscopy, which takes longer again.

We may have some results available while you are still in hospital but would need to allow six weeks to be sure that the other results are back.

The specialist performing the procedure will confirm after the procedure if you need follow up in six weeks.

If so, you need to make sure that when you leave the hospital, you have the appointment booked.

If you have any questions, please speak to you child’s doctor or nurse or call Interventional Radiology:

Telephone: 020 7405 7943

You can also contact us through MyGOSH.