What Is a Kidney Biopsy?

A kidney biopsy—also known as a renal biopsy—is the gold standard test for diagnosing several types of kidney diseases. During a kidney biopsy, a healthcare provider takes a small sample of tissue from your kidneys by using a needle that enters the skin through your back. usually by entering through the skin of your back. 

Typically, a radiologist (a doctor who specializes in medical imaging procedures) or a nephrologist (a doctor who specializes in the kidneys) performs a kidney biopsy. A pathologist (a doctor who specializes in analyzing tissue samples) then checks the kidney tissues under a microscope and determines whether you have kidney disease.

Purpose

A kidney biopsy takes a closer and more detailed look at your kidneys. Taking a sample of your kidney tissue allows healthcare providers to check the function of your kidneys, diagnose kidney disease, and monitor a pre-existing kidney disease over time.

Helps Diagnose Kidney Disease

Your healthcare provider may suggest that you get a kidney biopsy if they suspect you have kidney disease or if you're experiencing kidney disease symptoms, but the cause of your symptoms is unknown.

Sometimes, your healthcare provider might already know what's causing your symptoms. For example, most people who have kidney disease related to long-term diabetes don’t usually need to get a biopsy. This is also often true for people who have kidney disease from prolonged very high blood pressure.

But other times, you might have certain symptoms of kidney disease, such as blood in your urine or swelling in your legs that may be unexplained. In such cases, your provider will recommend a kidney biopsy to determine what exactly is causing your symptoms.

Monitors Underlying Kidney Diseases

Sometimes a kidney biopsy is helpful if you’ve already been diagnosed with pre-existing kidney disease, but your healthcare provider wants to monitor the progress of your condition. If you're receiving treatment for your kidney disease, your healthcare provider may also suggest a kidney biopsy to see how well your body has been responding to treatment and make adjustments to your treatment plan if necessary.  

Types of Kidney Biopsies

There are different types of kidney biopsies, and your healthcare provider will recommend which one you need based on your symptoms and overall health condition. Your provider may suggest one of the following types of biopsies:

• Percutaneous kidney biopsy: The most common and least invasive type of biopsy which occurs when your provider inserts a thin needle through your back and into your kidneys to remove a small sample of tissue.
• Laparoscopic kidney biopsy: During this biopsy, you will be asleep under general anesthesia. A healthcare provider will make a small cut through your back using a tiny tool to retrieve a kidney tissue sample.
• Transjugular kidney biopsy: This type of biopsy occurs when your provider inserts a needle through a thin tube into a vein in your neck. They then guide the needle through the veins and eventually inside the kidneys to get a tissue sample.
• Open kidney biopsy: The least common of the kidney biopsies, this type uses larger into your skin to obtain a sample of tissue from your kidneys. While this exam is very rare now, if you receive this type of biopsy, it will require general anesthesia.
  

How Does It Work?

Before going in for a kidney biopsy, it's helpful to know how the test works and what you can expect from the process.

Before the Test

On the day of the test, it's important to arrive at the testing site early. Usually, you'll receive your test at your provider's office, a local clinic, or in the hospital. You'll likely be asked to fill out paperwork and medical waivers before the test begins, which may take a bit of time.

Once you're ready for the test, a healthcare provider will guide you into the testing room. Most people receive some type of sedative medication before the procedure. This sedative helps you feel sleepy and relaxed, but you'll still be awake. However, if you're receiving a type of kidney biopsy that requires general anesthesia, you will be put to sleep for the test.

In most cases, the sedative or anesthetic medication is administered via a needle that enters a vein in your arm. You may feel a bit of a sting when the needle goes into your arm, but the procedure should not hurt after you've received sedative medication. 

During the Test

When you're ready for the test, a healthcare provider will instruct you to lie on your stomach. If you're pregnant, your provider will likely conduct the test while you're seated to not add extra pressure on your stomach.

Once you're in the proper position, your provider will use an imaging technique, such as an ultrasound, to guide the needle into the correct spot. Before they enter the needle into your skin, your provider may tell you to hold your breath. Once the needle is entered, you may slowly breathe out as your provider collects the tissue samples.

In most cases, your provider may repeat this process multiple times to retrieve enough tissue samples. The reason they take several samples is so that the pathologist has enough tissue to analyze your kidneys and come to a conclusion about the status of your kidney health.

When your provider obtains the number of samples they need, they will bandage the skin on the entry sites of the needle to prevent any bleeding. The needle that providers use during a kidney biopsy is very small, so you will not need any stitches.

After the Test

In most cases, you can go home a few hours after the procedure is complete. But if your healthcare provider wants to monitor you longer, they may move you to an in-patient room to stay at the hospital overnight.

You'll likely know if you need to stay overnight before your test. Your healthcare provider will also advise you to pack an overnight bag with essentials, such as extra clothes, toiletries, and any medications you may be taking. But, it's also possible to stay overnight if you are showing unexpected signs of complications after the procedure. 

Once the procedure is over, it's normal to feel some pain in the area where the needle entered your skin. This pain can last up to a few days, but if the pain isn't going away, it's important to tell your provider. They may recommend over-the-counter pain medications to help relieve your symptoms. Your provider will also advise you to avoid any heavy lifting or strenuous exercise for a couple of weeks after the procedure to reduce pain and prevent any complications from occurring. 

Risks and Precautions

Excess bleeding or bruising is the most common risk after you have a kidney biopsy. If you lose a lot of blood, you may be at an increased risk of developing low blood pressure and anemia (a condition that occurs when your body doesn't have enough red blood cells).

It's also common for your urine to be slightly pink in color for a few days after the procedure. However, if your urine doesn't return to its normal color within a few days, contact your healthcare provider. In rare cases, pink-colored urine could be a sign of a rare complication known as arteriovenous fistula, which occurs when your arteries and veins (two different types of blood vessels) form an abnormal connection in your body.

In rare situations, it's also possible to develop an infection. If you notice symptoms like fever, lightheadedness, or excess blood loss, it's important to notify your healthcare provider right away so they can manage your symptoms as soon as possible.

It's worth noting that some people are at higher risk of experiencing complications from a kidney biopsy. If you carry extra adipose tissue (excess body fat around the waist), have hypertension, live with anemia, are pregnant, or have specific problems with your kidney (such as only having one kidney instead of two), you may be at a higher risk of infection or bleeding. Talk to your healthcare provider if you may be high-risk, as they are best fit to tell you about your options.

How to Prepare for a Kidney Biopsy

If your healthcare provider tells you that you need a kidney biopsy, it's important to be prepared for the procedure. In most cases, your provider will perform the biopsy at their outpatient clinic or a hospital. When you go in for your test, bring any paperwork they gave, your insurance card, and your ID.

In most cases, your provider will advise you to stop drinking and eating anything for eight hours before the procedure. If you're on medication, it's a good idea to ask your provider if you should stop taking your medications and how long you should be off of them before your test. You'll likely need to temporarily stop medications that help prevent blood clots, like Xarelto (rivaroxaban), as well as certain over-the-counter pain medicines, like Aleve (naproxen).

On the day of your appointment, it's helpful to wear loose clothes that you can easily remove, as you will likely be asked to change into a hospital gown before the procedure. Going in for your procedure may be scary. When your test date gets here, it may be helpful to bring a loved one to your appointment or have a ride arranged to pick you up after the procedure is over.

Medical procedures can be expensive, so it's important to know how much this test will cost. It's a good idea to call your hospital's billing department and your insurance company to ask what you may have to pay. If you don't have insurance, ask the billing department about your payment options and any support programs that can help offset costs.

Results

After the test is complete, you can expect to wait anywhere from a few days to a couple of weeks to get your test results back. A pathologist will view the sample tissue and then write up a report for your healthcare provider with an analysis of what they found in your sample. Your healthcare provider will then call you or set up a follow-up appointment to discuss your test results.

Unlike some other tests, results from a kidney biopsy don’t come back as “positive” or “negative.” Instead, the pathologist describes individual features of the kidney in detail, often using highly technical language. For example, the report might mention swelling, scar tissue, or some dead kidney cells in some parts of the sample. The report may also suggest signs of a blocked blood vessel or a type of immune system cell that isn’t normally present. 

Your healthcare provider will use the analysis from the pathologist's report and combine this information with your symptoms, health history, and other medical tests to reach a conclusion about the status of your kidney function. If the kidney biopsy doesn't give enough information to help your healthcare provider make a diagnosis, they may recommend additional tests or a repeat biopsy.

A Quick Review 

A kidney biopsy is the gold standard diagnostic test for many different kinds of kidney diseases. If you are experiencing symptoms of kidney disease without any underlying conditions, your provider may recommend a kidney biopsy to better understand your condition and symptoms.

During a kidney biopsy, a provider will remove a small sample of tissue from your kidneys and send it to a lab for testing. Once the test is complete, a pathologist will analyze the sample and report back with any conclusions about your sample to your healthcare provider. Your provider can then use that information to diagnose you with kidney disease and discuss next steps about your treatment plan, if needed.