Kidney Biopsy

A biopsy is a diagnostic test that involves collecting small pieces of tissue, usually through a needle, for examination under a microscope. A kidney biopsy can help find a diagnosis and determine the best course of treatment. Your doctor may recommend a kidney biopsy if you have any of the following conditions:

• haematuria which is blood in your urine
  
  
• proteinuria which is excessive protein in your urine
  
  
• impaired kidney function which causes excessive waste products in your blood
  

A pathologist will look at the kidney tissue samples to check for unusual deposits, scarring, or infecting organisms that would explain your condition. The doctor may discover that you have a condition that can be treated and cured. If you have progressive kidney failure, the biopsy may indicate how quickly the disease is advancing. A biopsy can also help explain why a transplanted kidney is not working properly.

Talk with your doctor about what information might be obtained from the biopsy and the risks involved so that you can help make a decision about whether a biopsy is worthwhile in your case.

Preparation

You will have to sign a consent form indicating that you understand the risks involved in this procedure, although they are very slight. Discuss these risks thoroughly with your doctor before you sign the form.

Make sure your doctor is aware of all the medicines you take and any drug allergies you might have. You may be told to avoid food and fluids for 8 hours before the test. Shortly before the biopsy, you will give blood and urine samples to make sure you don't have a condition that would make doing a biopsy less desirable.

Test Procedures

Kidney biopsies are usually done in a hospital. You may be fully awake with light sedation, or you may be asleep under general anaesthesia. If you are awake, you will be given a local anaesthetic before the needle is inserted.

You will lie on your stomach to position the kidneys near the surface of your back. If you have a transplanted kidney, you will lie on your back. The doctor will mark the entry site, clean the area, and inject a local painkiller. For a percutaneous (through the skin) biopsy, your doctor will use a locating needle and x-ray or ultrasound equipment to find the right spot and then a collecting needle to gather the tissue. You will be asked to hold your breath as the doctor inserts the biopsy needle and collects the tissue, usually for about 30 seconds or a little longer for each insertion. Do not exhale until you are told. You may feel a small "popping" sensation as the needle enters the kidney. The doctor may need three or four passes to collect the needed samples.

The entire procedure usually takes about an hour, including time to locate the kidney, clean the biopsy site, inject the local painkiller, and obtain the tissue samples.

Some patients shouldn't have a percutaneous biopsy because they are prone to bleeding problems. These patients may still undergo a kidney biopsy through an open operation in which the surgeon makes an incision and can see the kidney to obtain a biopsy. Another method is the transjugular biopsy. To obtain the tissue sample, the needle is inserted through a catheter that enters the patient's jugular vein at the neck. The needle threads down through the blood vessel to the right kidney in order to obtain the tissue from the inside without puncturing the outside skin of the kidney.

After the Test

You should lie on your back for 12 to 24 hours. During this time, your back will probably feel sore. If you have a transplanted kidney, you will lie on your stomach. You will likely stay in the hospital overnight after the procedure so that staff can check your condition. You may notice some blood in your urine for 24 hours after the test. To detect any problems, your team will monitor your blood pressure and pulse, take blood samples to measure the amount of red cells, and examine the urine that you pass. On rare occasions when bleeding does not stop on its own, it may be necessary to replace lost blood with a transfusion.

A rare complication is infection from the biopsy procedure.

Tell your doctor or nurse if you have any of these problems:

• bloody urine more than 24 hours after the test
• inability to urinate
• fever
• worsening pain in the biopsy site
• faintness or dizziness

Getting the Results

After the biopsy, the doctor will inspect the tissue samples in the laboratory under one or more microscopes, perhaps using dyes to identify different substances that may be deposited in the tissue. It usually takes a few days to get the complete biopsy results. If your case is urgent, you may have a preliminary report within a few hours.