A kidney biopsy is a procedure in which a health care professional takes one or more tiny pieces of tissue from your kidney. A pathologist examines the tissue samples under a microscope for signs of damage or disease.

A kidney biopsy can help health care professionals diagnose and treat kidney problems when they need more information after looking at your blood and urine tests. A biopsy may be recommended if your lab test results show any of these conditions

• persistent blood in your urine, known as hematuria
• too much protein in your urine, known as proteinuria
• problems with kidney function, which can cause waste products to build up in your blood

A kidney biopsy can help health care professionals

• check for signs of kidney inflammation, scarring, infection, or unusual deposits of a protein called immunoglobulin
• identify which parts of your kidney are damaged and how likely it is the damage will get worse
• determine the best way to treat your kidney problem

If you have a transplanted kidney that is not working properly, the biopsy can help your health care professional find the cause.

In some cases, a kidney biopsy may be used to examine an abnormal mass, or lump, seen on a kidney x-ray or ultrasound and help rule out kidney cancer.

Talk with your health care professional

Talk with your health care professional about what you can expect before, during, and after the kidney biopsy. If you have high blood pressure, your health care professional may discuss ways to control your blood pressure before the procedure. High blood pressure that is not well controlled by medicines can increase the risk of bleeding after a kidney biopsy.

Some medicines and supplements can increase the risk of bleeding or affect how you respond to sedatives or anesthesia. Review with your health care professional all your prescribed and over-the-counter medicines, vitamins, and supplements, including

• aspirin
• nonsteroidal anti-inflammatory drugs (NSAIDs)
• blood thinners

Tell your health care professional about any allergies you have to medicines or foods.

Follow your health care professional’s instructions

As your health care professional advises

• make any needed changes to the medicines and supplements you take
• have blood tests and imaging tests—such as a computed tomography (CT) scan or ultrasound—to prepare for the procedure
• make plans to get a ride home after the kidney biopsy
• fast for several hours before the procedure
• arrive 90 minutes to 2 hours before the procedure to sign a consent form and have any needed tests

The kidney biopsy is usually performed by a radiologist or nephrologist at a hospital or outpatient center.

Percutaneous kidney biopsy

A health care professional inserts a thin biopsy needle through your skin and into your kidney to obtain samples of your kidney tissue for analysis. Most kidney biopsies are done this way.

The procedure usually takes about an hour. In most cases, you will lie face down with a firm pillow or sandbag under your body. If you have a transplanted kidney, you will lie on your back, because health care professionals place transplanted kidneys in the front-lower part of the abdomen. If you are pregnant or have severe obesity, the procedure may sometimes be done while you are lying down, seated, or in another position that is comfortable for you.

A health care professional may give you an intravenous (IV) sedative through a line placed in a vein in your arm or hand before the biopsy. The sedative will help you stay comfortable during the procedure. After marking the spot where the needle will enter your skin, a health care professional will clean the area and inject a local anesthetic to numb the area.

Next, a health care professional will use imaging methods—most often, an ultrasound—to guide the biopsy needle. The health care professional may insert the needle more than once to obtain enough tissue for a diagnosis. The needle often has a trigger to make sure it goes in and out of the kidney quickly, and it can make a clicking or popping sound, which is normal. The health care professional may ask you to hold your breath for a few moments during the biopsy.

After the biopsy, no stitches are needed. A health care professional will place a bandage over the spot where the needle went into your skin.

Other methods

If a percutaneous kidney biopsy is not a good option for you, your health care professional may recommend one of the following procedures.

Laparoscopic kidney biopsy

A health care professional makes two small cuts into your back and inserts special tools to view your kidney and collect tissue samples. The procedure is done while you are under general anesthesia.

Transjugular kidney biopsy

A health care professional inserts a catheter and needle into a vein in your neck called the jugular vein. The biopsy needle is guided through your veins and into your kidney to collect a tissue sample. This method of obtaining kidney tissue is used less often than the laparoscopic method.

Open kidney biopsy (open surgery)

A health care professional makes a small cut in your skin close to your kidney, takes a small tissue sample, and stitches the cut closed. This procedure requires general anesthesia and is used rarely.

Recovery

After a kidney biopsy, you can expect to

• lie down in a recovery room for several hours while your blood pressure, pulse, and urine are monitored. A health care professional will also check to make sure there is no internal bleeding at the biopsy site.
• be released to rest at home. In some cases, you may need to stay overnight at the hospital.
• have some pain or soreness near the biopsy site. You may also pass urine that is pink or slightly cloudy for up to 24 to 48 hours after the procedure.
• wait 2 weeks before resuming strenuous activities, such as heavy lifting or participating in contact sports.

Biopsy results

After the biopsy, your kidney tissue will be sent to a lab to be examined by a pathologist. Biopsy results may take a few days or longer to come back. In urgent cases, your health care professional may receive a preliminary report within 24 hours. Your health care professional will review the results with you during a follow-up visit.

The risks of a kidney biopsy include

• bleeding from the biopsy site. A small amount of bleeding is common after a kidney biopsy. The bleeding is rarely serious enough to require treatment or a blood transfusion. Bleeding that is serious enough to require surgery or cause the loss of a kidney is very rare.
• pain at the biopsy site, which is usually mild and goes away a few hours after the procedure.
• infection, which is rare.

Seek medical help right away if you have any of these symptoms after a kidney biopsy

• can’t urinate, have to urinate very often, feel an urge to go to the bathroom right away, or have a burning feeling when urinating
• have urine that is dark red, brown, or has blood clots
• feel worsening pain at the biopsy site
• see redness, swelling, bleeding, or other drainage from the biopsy site
• have a fever
• feel faint or dizzy