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 small sample of kidney tissue being removed.
A kidney biopsy is done to diagnose and monitor certain conditions of the kidney. 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 it done?
Your kidneys lie just under the ribcage, towards the side and back of your upper 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 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 The needle is inserted and withdrawn quickly, bringing with it a small sample of kidney tissue.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.
What preparation is needed before a kidney biopsy?
You will usually have a blood test done shortly before the biopsy to check how well your blood will clot. This is 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 and warfarin, for one week before the biopsy. (You may need to discuss your medication with your doctor if you take such medicines for other conditions.)
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.
What are the risks of kidney biopsy?
Complications are uncommon. In a small number of cases there is some bleeding from the biopsy site. This is usually minor, and soon stops. Occasionally, the bleeding is more severe. Rarely, the bleeding requires a blood transfusion and/or an operation to deal with it. The main reason that you are monitored for several hours after the biopsy is to check for bleeding. There is a small risk that the small wound will become infected after the biopsy.
After a kidney biopsy
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 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 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 develop abdominal pain.
- The biopsy site becomes red or angry looking.
- You develop a fever or temperature.
- The biopsy site is still painful three days later and painkillers do not help.
Dr Rachel Hoad-Robson
Dr Gurvinder Rull
Prof Cathy Jackson