What is a kidney biopsy?
A kidney biopsy involves taking one or more tiny pieces (samples) of kidney tissue for examination with a microscope. The microscopes make it possible to see the samples in greater detail.
The biopsy sample may be taken in one of two ways:
- Percutaneous (through the skin) biopsy: a needle placed through the skin that lies over the kidney and guided to the right place in the kidney, usually with the help of ultrasound.
- Open biopsy: the kidney sample is taken directly from the kidney during surgery.
The kidney sample is then sent to a doctor (pathologist) who looks at it with microscopes. He or she will check for any signs of disease.
Why is a kidney biopsy performed?
Some kidney problems can often be found with blood and urine tests, a sonogram (an image made by ultrasound) or other special x-rays, and a physical exam rather than a biopsy.
Specific reasons to do a kidney biopsy include:
- Hematuria—blood in the urine, which can be a sign of kidney diseaseor other urinary problems.
- Albuminuria—a condition in which the urine has more-than-normal amounts of a protein called albumin. Albuminuria may be a sign of kidney disease.
- Changes in kidney function, which can cause the buildup of waste products in the blood.
- Abnormal blood test results
- Acute or chronic kidney disease with no clear cause
- Nephrotic syndrome and glomerular disease (which happens when the filtering units of the kidney are damaged)
The kidney tissue sample can show inflammation, scarring, infection, or unusual deposits of a protein called immunoglobulin. If a person has chronic kidney disease—any condition that causes reduced kidney function over a period of time—the biopsy may show how quickly the disease is advancing. A biopsy can also help explain why a transplanted kidney is not working properly.
A kidney biopsy may also help to find:
- If a disease is getting better with treatment or if it is getting worse. It may also show a problem that cannot be cured, but can be slowed down by other therapy.
- How much permanent damage has happened in the kidney?
- Why a transplanted kidney is not working well and helps your doctor decide on further treatment.
- A kidney tumor.
- Other unusual or special conditions.
- If a certain treatment is hurting your kidneys
How is a kidney biopsy performed?
The procedure typically takes about an hour and includes the following steps:
- Most people will lie on their abdomen on an examination table. The technician will place a firm pillow or sandbag under a person’s body to support the abdomen and help push the kidneys up toward the person’s back and the surface of the skin. People who have a transplanted kidney lie on their backs because surgeons place transplanted kidneys in the front-lower part of the abdomen, to one side of the bladder.
- A nurse or technician will give the person sedatives through the IV.
- The health care provider will mark the point where the needle will enter the skin, clean the area, and inject a local anesthetic to numb the area.
- Next, the health care provider uses imaging techniques, such as ultrasound, to guide the biopsy needle into the kidney. Ultrasound uses a device called a transducer that bounces safe, painless sound waves off organs to create an image of their structure. Sometimes the health care provider uses a computerized tomography scan or magnetic resonance imaging to guide the needle into the kidney.
- The health care provider will ask the person to hold his or her breath and stay still as the health care provider inserts the biopsy needle and removes the kidney tissue. When the health care provider takes the biopsy, the instrument will make a clicking or popping noise. The health care provider may need to insert the needle three or four times. People most often will need to hold their breath for about 30 seconds or a little longer for each insertion.
The doctor uses imaging techniques such as ultrasound to guide the biopsy needle into the kidney.
For people with bleeding problems, the health care provider uses a laparoscope—a thin tube with a video camera. This procedure is surgery that requires general anesthesia. The surgeon makes a small incision into the back and inserts the laparoscope to see the kidney. The surgeon can insert tiny tools through the laparoscope to collect tissue samples and can watch after the procedure through the camera to make sure that if there is any bleeding, he or she can stop it.
How is the biopsy done?
A kidney biopsy is usually done in a hospital. An overnight stay may be needed to watch for any problems. You may be awake with only light sedation, or asleep under general anesthesia. You will be lying face down with a pillow under your rib cage. If the biopsy is done on a transplanted kidney, you will be lying on your back.
- Percutaneous biopsy:
The kidney is found using a sonogram, x-ray images, or both. Sometimes, an injection of dye into your veins may be needed to help the doctor find the kidney and important blood vessels. Once the biopsy site is found, your skin is marked, and cleaned where the biopsy needle will be inserted. You will receive a local anesthetic to numb the area where the biopsy needle enters. You will be asked to take in a deep breath and hold it as the doctor puts in the needle. When the needle pushes through the skin to the kidney, you may feel a “pop” or pressure. It is important to stay still and to hold your breath (about 45 seconds or less). Sometimes two needle passes are needed to get enough of the kidney sample for diagnosis. When enough is taken, the needle is removed and a bandage is placed over the needle puncture site. The entire procedure, from start to finish, usually lasts about one hour. Sometimes the biopsy may take longer than an hour.
- Open kidney biopsy:
Some patients should not have a percutaneous biopsy because they may have a history of bleeding problems. For these patients, an open operation may be done where the surgeon can actually see the kidney to get a good sample to study.
What are the risks of a kidney biopsy?
The risks of a kidney biopsy include
- Bleeding—the most common complication of a kidney biopsy. Bleeding may come from the kidney or the puncture site. Bleeding from the kidney rarely requires a blood transfusion.
- Infection—a rare complication of a kidney biopsy. Health care providers prescribe bacteria-fighting medications called antibiotics to treat infections.
Points to remember:
- Before the biopsy:
- Talk with your nephrologist to make sure you understand the need for a biopsy and the risks and benefits.
- Tell your doctor about any allergies you have and medicines you take.
- Avoid blood thinning medications and supplements.
- Avoid food and fluid for eight hours before the test.
- After the biopsy:
- Follow up with your nephrologist.
- Rest in bed for 12 to 24 hours.
- Avoid blood thinning medications.
- Report any problems, such as:
- Bloody urine for more than 24 hours after the biopsy
- Unable to pass urine
- Worsening pain at the biopsy site
- Feeling faint or dizzy