What is a Renal biopsy?
A kidney biopsy (also known as a renal biopsy) is an important test to diagnose kidney disease and to monitor kidney transplants. A biopsy is a very small sample which is used to examine kidney structure in minute detail. The reason for the biopsy will usually be discussed with you in the outpatient clinic. In some cases it may be an urgent test that is done during a hospital stay.
Will I need to come into hospital?
You are usually admitted to the ward on the morning of the biopsy, where a nurse or doctor will ensure that your medical condition has not changed since your last visit. Your blood pressure will be measured, urine checked, and blood tests may be sent. You may be examined. Too high blood pressure could delay the biopsy.
You should usually not have taken aspirin or clopidogrel, or pain killers containing aspirin, for 1 week before the biopsy (but the precise timing of when you should stop should be discussed with you, according to the reason for taking these drugs).
How is the biopsy performed?
All renal biopsies are done by a doctor in the radiology (X-ray) department using an ultrasound scanner to view the kidney during the biopsy. The biopsy is taken from one kidney.
If it is a biopsy of your own kidney, you are asked to lie on your tummy. The skin over your back just below the ribs is cleaned with antiseptic. Some local anaesthetic is put into the skin which stings a little at first. More local anaesthetic is then put into the muscle of the back. When the skin and tissues are completely numb the doctor localises the kidney with ultrasound and then takes the biopsy with a needle. You are usually asked to take a breath in, then hold it for a few seconds while the biopsy is taken. This may be repeated a few times to ensure an adequate sample. You should not be aware of any pain but may feel a little pressure when the biopsy needle is used.
If it is a biopsy of a transplant kidney you will be asked to lie on your back, and the local anaesthetic will be put into the skin and then the muscles of your tummy over the transplant. The biopsy is then taken in the same way.
What happens after the biopsy?
Following the biopsy you will return to the ward where you will rest in bed for at least 6 hours. We ask for 2 hours lying flat and then 4 hours sitting up. Your blood pressure and pulse will be measured frequently at first and then at regular intervals. The first urine you pass should be given to the nurse, to see if there is any bleeding. You will be able to eat and encouraged to drink plenty of fluids. You can usually be allowed to go home later that day or the morning after the biopsy.
You should avoid strenuous activity, heavy lifting or contact sports for a week or two after the biopsy.
When do I get the results?
It generally takes 48 hours for the laboratory to give a preliminary report and at least a week to get a full report. Your doctor will discuss the results of the biopsy with you at the clinic shortly after the biopsy, and these will also be sent to your GP. If the test is being done urgently, some results may be available within 24 hours.
Is it possible to have the test as a day case?
Patients who are otherwise healthy with good kidney function may be able to go home on the same day. This must be planned in advance so that you can arrive early in the morning, have the biopsy done, and be monitored with blood pressure recordings for 6-8 hours after the biopsy. You must have passed urine and show no signs of bleeding before being allowed home.
What are the risks of renal biopsy?
Complications of renal biopsy are rare. The most important is bleeding, and you are monitoried after the biopsy to detect this. Changes in pulse rate, blood pressure and blood in the first urine after the biopsy may be signs of bleeding. If there are signs of much bleeding you may need to go back to the radiology department for an ultrasound scan to see if there is a clot outside the kidney. The majority of bleeding is minor and needs no special treatment.
If there is an unexpected amount of bleeding, you may need a blood transfusion, and in very rare cases a further special X-ray called an angiogram is done to find the bleeding point, and sometimes to stop the bleeding. Very rarely an operation to remove the kidney may be required. Visible blood can appear in the urine in 3-5% of cases. Requiring a blood transfusion or angiogram is very rare, less than 1% of biopsies.
|Complications of renal biopsy||Rate||Comment|
|Visible blood in urine||3-5%||Usually settles on its own|
|Needing a blood transfusion and angiogram||<1%||Bleeding causes a drop in blood count|
|Needing an operation||<0.1%||This is very rare|
You may have some pain or discomfort after the biopsy. You can take paracetamol 1-2 tablets every 8-12 hours for the first day. If you have more severe pain after the biopsy, you should contact the renal unit.
There is a small risk that pre-existing heart or breathing problems may be made worse by sedation. We do not use sedation routinely but it can be given if you are particularly anxious.
Do not take any aspirin, aspirin containing pain killers or anti-inflammatory drugs for 1 week after the biopsy – unless you have been given other instructions.
Our Patient Information Leaflet on Renal Biopsy can be downloaded here (.pdf)
Acknowledgements: This page was edited by Gemma Browne based on an information leaflet by Dr CP Swainson. It was revised in July 2002 by Anne Petherick. The date is was last modified is shown in the footer.