Kidney biopsy

You might need a kidney biopsy at Great Ormond Street Hospital (GOSH) so doctors can make a diagnosis or see how your kidneys are responding to treatment. 

It’s a procedure to remove a very small piece of kidney tissue to be examined under a microscope.

A kidney biopsy may be needed when blood and urine tests, ultrasound scans and other radiology imaging have not been able to give doctors enough information about your kidney problem.

Some problems that might need a kidney biopsy include:

  • Blood frequently appearing in your urine.
  • Large amounts of protein in your urine, such as in nephrotic syndrome.
  • Your kidney function has deteriorated rapidly and it’s not known why.

kidney biopsy after transplant (480.0 KB)

If you’ve had a kidney transplant, a biopsy can identify why your kidney isn’t working well and what treatment you need. You can find out more information about this in our  leaflet.


We need to be sure that your 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’ll talk to you about whether or not you need to come in the night before or on the day of the biopsy and how long you should avoid fluid or food.

As a teenager, you may have your kidney biopsy under a local anaesthetic, usually Entonox® (the ‘gas and air’ women have during childbirth). Younger children may have a full general anaesthetic. We’ll talk about the best approach for you.


Once you’re under general anaesthetic or have had Entonox® you’ll lie on your left side if your own kidney (native kidney) is being biopsied. When you have two kidneys, we usually take a biopsy from the one on the right hand side. If the biopsy is on a transplanted kidney, you’ll lie on your back, as this makes it easier to reach the transplanted kidney. The exact position of the kidney 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 your skin at the biopsy site and along the path between the skin and the kidney. The only cut that is made is a tiny nick in the skin to allow the biopsy needle to enter more easily. This nick is 2mm to 3mm long and is so small and is so small that it does not need a stitch afterwards.

The biopsy needle has a hollow centre, and when it’s removed, it brings a very fine core of kidney with it. This is about the size of a grain of rice and is approximately 1cm to 2cm long. This tiny piece of kidney will contain between 10 and 50 glomeruli, which are the little filtering units within the kidney. This will not affect kidney function as each kidney contains about a million glomeruli. Usually two or three samples are taken so that enough tissue is available for testing in our laboratories.

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

The biopsy site will be covered with a dressing. The area usually oozes slightly straight after the procedure, but this will stop when pressure is applied to the site. You will then return to the ward where you need frequent observations of your heart rate, breathing and blood pressure to make sure your body has not been upset by the biopsy – very rarely someone can bleed after a kidney biopsy. For this reason, we need you to lie as still as you can for four hours or more.


You may get a little bit of pain (like a bruise pain) over the biopsy site, but this isn’t usually serious. Paracetamol is usually enough to help with the pain– follow your doctor’s advice about this. It’s common to get a little bruising around the kidney which settles quickly. You may see that your urine (wee) is slightly pink as it’s common for a small amount of blood to leak into the urine afterwards. This usually settles within the first 24 hours and is normal. Occasionally, heavier bleeding can cause blood clots to form in the urine.

Another very rare 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. This can be diagnosed with an ultrasound and you will usually need a ‘keyhole’ procedure to treat it.

Going home

You can be taken home about four to six hours after the biopsy if you’re well after the procedure. This means that you should be eating and drinking and have passed urine (peed) that is not heavily blood stained on two occasions.

We will check that the biopsy site looks fine and that your vital signs (blood pressure, pulse and breathing) are normal. If the biopsy took place late in the afternoon, you may need to stay overnight and go home the following morning.

At home

  • Keep the dressing dry and in place for two to three days after the procedure. This helps the biopsy site to heal and reduces the risk of scarring. The dressing can then be removed.
  • You 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 take paracetamol (given according to the instructions on the bottle) unless you have been advised otherwise – follow your doctor’s advice about this.
  • Your urine may look slightly pink afterwards due to a small amount of bleeding. This will usually settle down within 24 hours.
  • When you get home you should take it easy and not run around or ride a bike for two weeks. We advise that you stay off school for two days after the biopsy. You should avoid contact or impact sports such as rugby, football, trampolining or horse riding for the next four weeks to allow the kidney to heal properly. 
You or an adult should call the ward if:

  • You have obvious blood or clots in your urine (wee).
  • The biopsy site is very painful – for example, normal pain relief is not helping and you are unable to get up or walk in the days after discharge.
  • There is any oozing or bleeding from the biopsy site.
  • You develop a fever.

Your results

The biopsy is processed in three different ways. First of all, 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’re still in hospital, but would need to allow six weeks to be sure that the others are back. You need to make sure that when you leave the hospital, you have an appointment for six weeks or sooner if you are asked to do so.

Compiled by:
Great Ormond Street Hospital
Last review date:
July 2014