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Introduction

This web page tells you about having a kidney biopsy. Please read it as well as talking to your doctor/nurse.

What is a kidney biopsy?

A kidney or renal biopsy means removing a very small sample (about half a matchstick in size) from one of your kidneys using a special needle, not open surgery. The sample can then be tested under a microscope to find out the cause of your kidney disease.

Why would you need to have a kidney biopsy?

You will know that blood or urine tests have shown that your kidneys are not working properly. A biopsy may be used to find the cause of the kidney disease and tell what the best treatment is.

Where is it done?

The biopsy will usually be carried out in either the ward, a special procedure room, the operating theatre or the X-ray department. It takes about thirty minutes and will usually be done under local anaesthetic so you will remain awake. You can eat and drink normally before and after the biopsy is done.

How is it done?

You will usually be asked to lie face down on the bed or couch with a pillow under your stomach. Usually, the exact position of the kidney will be found using an ultrasound machine. The skin on your back over the kidney will be cleaned with antiseptic, and local anaesthetic will be injected into the skin. It may sting at first and once the skin is numb more local anaesthetic is injected around the kidney. The biopsy needle will then be passed through the numb area and the kidney sample taken. You will be asked to hold your breath for a few seconds as the kidney moves during breathing. You should usually not be aware of any pain from the biopsy needle but you may feel a little pressure and hear a clicking sound when the biopsy sample is taken. The doctor may ask to take two or three biopsy samples and occasionally it will not be possible to remove a suitable bit of the kidney.

What happens next?

Afterwards you will be asked to rest in bed for at least six hours. Your pulse and blood pressure will be monitored and when you pass urine it will be tested for bleeding. During this time you can eat normally and will usually be encouraged to drink plenty of fluids. When the local anaesthetic wears off you may feel some pain in the back due to slight bruising for which you can be given a mild painkiller.

A provisional result of the biopsy should be available within 24-48 hours but the full report may take longer. If you feel well after the biopsy and have no pain or bleeding you may be able to go home later that day or the following day to rest. After the biopsy you should avoid exercise for 48 hours and vigorous activity for up to 2 weeks. If you develop severe pain around the kidney or any blood in the urine, you should contact the kidney unit straight away.

What are the risks of a kidney biopsy?

The risk of a serious complication is small. The main risk is that the biopsy needle can damage the kidney or other parts of the body nearby. This risk is reduced by the use of ultrasound scanning during the procedure. Your doctor has recommended a kidney biopsy because it is felt that the information from the biopsy makes this small risk worthwhile and it is important that you agree about this.

Bleeding is the most serious complication. You will have a blood test before the biopsy to make sure your blood clots normally. It is important that you tell your doctor if you have any problem with easy bleeding or bruising or if you are taking tablets that can affect bleeding such as ASPIRIN, CLOPIDOGREL, WARFARIN, APIXABAN, RIVAROXBAN, or other similar medications.  Normally these will need to be stopped several days before the procedure. You should also tell your doctor if you are allergic to antiseptic such as IODINE.

In about 1 in 10 biopsies there is visible bleeding in the urine that settles by itself.

In less than 1 in 50 biopsies there is more bleeding that requires a blood transfusion.

In less than 1 in 1500 biopsies the bleeding may continue and require urgent X-ray tests or even an operation to stop the bleeding.

In less than 1 in 3000 biopsies the kidney may have to be removed to stop the bleeding. Although deaths have occurred following complications of biopsies, this is extremely rare.

What are the benefits of having a kidney biopsy?

A biopsy could help to find out what is wrong with your kidneys and decide about the correct treatment. It may avoid you being given unnecessary treatment which could have side effects and it may prevent further harm being done to your kidneys by being given the wrong treatment.

What are the alternatives?

A biopsy is usually the last test to be done to work out what is wrong with your kidneys because the other tests have not provided the answer. Without a biopsy your doctor may not be able to advise the best treatment for you. Your doctor should be able to tell you what changes in treatment could be made for your kidneys if you decide not to have a biopsy taken first.

If you agree to have the biopsy you will be asked to sign the hospital’s consent form which will state that you have received information about the procedure and have discussed it with your doctor.

Last reviewed August 2025
Next review August 2028

Reviewed by Dr Oshini Shivakumar, MBBS, MA(Cantab), MRCP
Renal Specialist Registrar,
Imperial College Healthcare NHS Trust

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The National Kidney Federation cannot accept responsibility for information provided. The above is for guidance only. Patients are advised to seek further information from their own doctor.