A kidney biopsy involves taking a small sample of tissue from the kidney. Cells from the kidney can then be looked at in detail. It is used to diagnose and monitor certain conditions.
Note: the information below is a general guide only. The arrangements, and the way tests are performed, may vary between different hospitals. Always follow the instructions given by your doctor or local hospital.
What is a kidney biopsy?
A biopsy is a procedure in which a small sample of tissue is removed from a part of the body. The sample is looked at under a microscope, or tested in other ways. A kidney biopsy (sometimes called a renal biopsy) involves a very small sample of kidney tissue being removed.
What will a kidney biopsy reveal?
A kidney biopsy is done to diagnose and monitor certain types of kidney disease. For example, inflammation of the kidney, which can be due to various causes, or cancer of the kidney. It is also used to monitor kidney transplants.
How is a kidney biopsy done?
Your kidneys lie just under the ribcage, towards the side and back of your upper tummy (abdomen). So, you will usually be asked to lie on your front on a couch or bed. The skin over a kidney is cleaned with antiseptic. Local anaesthetic is then injected into a small area of skin and tissues just over the kidney to be sampled (biopsied). This stings a little at first but then makes the skin numb.
If the biopsy is of a transplanted kidney, you will be asked to lie on your back and the local anaesthetic is put into the skin over the transplant.
A special hollow needle is then pushed through the skin and muscle into the kidney tissue to obtain a small sample. Because of the local anaesthetic, you should not feel any pain. However, you may feel some pressure as the doctor pushes on the needle. The needle is inserted and withdrawn quickly, bringing with it a small sample of kidney tissue.
You will have to hold your breath for 5-10 seconds when the needle is pushed in and out (you will be told exactly when). This is because the kidneys move slightly when you breathe in and out.
During the biopsy an ultrasound scanner is often used to help the doctor. The ultrasound scan locates the kidney so the biopsy needle is inserted at exactly the right place. The scan is painless.
Kidney tissue can also be obtained via a ureteroscope. In this procedure a small tube is passed through the urethra, up into the bladder and then up into the ureters which connect the bladder to the kidney. This is a less common method of obtaining a kidney biopsy. It will require a general anaesthetic and intravenous antibiotics.
How long does a kidney biopsy take?
The biopsy procedure itself usually takes between 15 minutes to half an hour.
There is a recovery period of a several hours afterwards (see below).
How to prepare for a kidney biopsy
You will usually have a blood test done shortly before the sample (biopsy) is taken. This checks how well your blood will clot - to make sure that you are not likely to bleed following the biopsy.
You may be advised not to take any medicines that affect blood clotting, such as aspirin, clopidogrel, dabigatran, rivaroxaban, edoxaban, apixaban, warfarin before the biopsy. Tell the team organising the biopsy if you are taking these, at least two weeks before the procedure. They will tell you when you need to stop and restart them. Don't stop taking these without medical advice.
You will need to sign a consent form at some point before the procedure to say that you understand what it involves and the risks and agree to allow the doctor to perform the procedure.
Is a kidney biopsy dangerous?
A kidney biopsy is generally a safe procedure. Complications are uncommon. However, they can occur. Risks include:
- Pain or discomfort at the biopsy site. This can usually be managed with simple painkillers.
- Blood in the urine. This happens in about 1 in 10 procedures and almost always settles down on its own.
- Bleeding from the biopsy site or internally around the kidney.
- This is usually minor and stops quickly.
- Rarely, the bleeding can be heavier.
- About 1 in 100 to 1 in 200 procedures cause bleeding that requires a blood transfusion.
- About 1 in 200 to 1 in 500 procedures require an X-ray guided procedure (embolisation) to stop the bleeding.
- Very rarely, an emergency operation is needed to stop the bleeding.
- Infection around the biopsy site, although this is very uncommon.
- Sometimes, the biopsy sample isn't enough for analysis under the microscope. This means the biopsy may need to be repeated.
Kidney biopsy after-care
You will need to lie on a bed and be observed for several hours to check that you have no bleeding. So, you may wish to bring in a book or a music player for this time. If you come into hospital for the test, you may need to stay in overnight.
However, if the sample (biopsy) was done early in the morning, you may be able to go home later in the day. You may have some discomfort which is usually eased by painkillers. The result of the biopsy may take a week or so to come back.
Your doctor may advise you not to take part in contact sports such as rugby or do any heavy lifting for a certain length of time after the procedure. This is to make sure the kidney has a chance to heal properly.
You should seek medical advice if:
- Your urine appears blood-stained.
- You are unable to pass urine.
- You develop tummy (abdominal) pain.
- The biopsy site becomes red or angry looking.
- You develop a high temperature (fever).
- The biopsy site is still painful three days later and painkillers do not help.
Further reading and references
Bandari J, Fuller TW, Turner capital I, Ukrainiansmall i, Ukrainian RM, et al; Renal biopsy for medical renal disease: indications and contraindications. Can J Urol. 2016 Feb23(1):8121-6.
Bakdash K, Schramm KM, Annam A, et al; Complications of Percutaneous Renal Biopsy. Semin Intervent Radiol. 2019 Jun36(2):97-103. doi: 10.1055/s-0039-1688422. Epub 2019 May 22.