An Overview of Kidney Biopsy (Renal Biopsy)

A kidney biopsy (also known as renal biopsy) is the removal of a small sample of tissue from the kidney. Cells from the kidney can then be looked at in detail in the laboratory. A renal biopsy is used to diagnose and monitor certain medical conditions, including the functioning of a transplanted kidney. The procedure is performed on an outpatient basis or in hospital. Preparation, biopsy, and recovery may take several hours.

In this article:
What is a kidney biopsy?
Why might I need a kidney biopsy?
What are the risks of a kidney biopsy?
What are contraindications of renal biopsy, if any?
How do I get ready for a kidney biopsy?
What happens during a kidney biopsy procedure?
What happens after the kidney biopsy?

Note: the information below is a general guide only. The arrangements, and the way tests are performed, may vary between different hospitals. Always follow the instructions given by your doctor or local hospital.

What is a kidney biopsy?

A biopsy is done to remove tissue or cells from the body to examine under a microscope. The tissue sample is removed usually with a needle to check for cancer or other abnormal cells. It also helps check how well the kidney is working. A doctor specially trained in kidney problems (nephrologist) usually performs this procedure, however, in some parts of the world, any healthcare provider who has been properly trained is allowed to perform it.

There are generally 2 types of kidney biopsies:

Needle biopsy (Percutaneous needle biopsy). After an anesthetic is given, the doctor inserts the biopsy needle into the kidney to get a sample. Ultrasound or computerized tomography (CT scan) may be used to guide the needle. Most kidney biopsies are done using this technique as it allows for quicker recovery, causes less pain, and has fewer risks.
Open biopsy (Surgical biopsy). After an anesthetic is given, the doctor makes an incision in the skin and surgically removes a piece of the kidney. For example, transjugular and laparoscopic biopsies which are performed on patients with bleeding disorders, tumor, obesity, or a solitary kidney.
- Transjugular biopsy, also called transvenous, involves inserting a small tube through the jugular vein in the neck and guiding it to the kidney using ultrasound. A biopsy needle is passed through the tube to the kidney to obtain a tissue sample.
- Laparoscopic biopsy involves using an endoscope (thin, lighted telescopic instrument) to explore the abdomen. Gas is introduced into the abdomen to separate the organs and to allow the laparoscope to pass. The needle is then inserted through the laparoscope and guided to the kidney with ultrasound.

If your healthcare provider wants to sample a specific area of the kidney, the biopsy may be guided by ultrasound, fluoroscopy, or computed tomography.

Why might I need a kidney biopsy?

Your kidneys are a pair of purplish-brown organs. They sit below the ribs toward the middle of the back. The kidneys:

Remove liquid waste from the blood in the form of urine
Keep a balance of salts and other substances in the blood
Produce erythropoietin, a hormone that aids the formation of red blood cells
Regulate blood pressure

When your kidney function is abnormal, a kidney biopsy may be done to:

Find out the reason for poor kidney function
Check how well a transplanted kidney is working.

There may be other reasons for your healthcare provider to advise a kidney biopsy.

What are the risks of a kidney biopsy?

As with any procedure, complications can happen including:

Bruising and discomfort at the biopsy site
On-going bleeding from the biopsy site, in the urine, or inside the body
Puncture of nearby organs or structures
Infection near the biopsy site

Although bleeding after a kidney biopsy occurs in as many as 10% of patients, only less than 1% of patients bleed so much as to require surgery, transfusion, or removal of that kidney to control the bleed.

If the kidney biopsy is done with the aid of X-ray, the amount of radiation used is small. Therefore, the risk for radiation exposure is low.

If you are pregnant or think you may be, tell your healthcare provider. Talk to your healthcare provider about the risks to the fetus from being exposed to an X-ray. Pregnancy is not always a contraindication for having a kidney biopsy. It may be important to maintain the health of the mother. Special precautions may be taken to protect both the mother and the fetus during a kidney biopsy.

You may not be able to have kidney biopsy if you have an active kidney infection, certain bleeding conditions, uncontrolled high blood pressure, or have only one working kidney.

There may be other risks depending on your specific medical condition. Be sure to raise any concerns with your healthcare provider before the procedure.

What are contraindications of renal biopsy, if any?

The most common contraindication to kidney biopsy is disease:

Bleeding disorder (e.g. inability to coagulate, platelet abnormality)
Hypertension
Pyelonephritis (disease of the pelvis of the kidney)
Shrunken kidney (i.e. as a result of disease)
Tumor

Nephrologists generally consider it safe for people with only one kidney (solitary kidney) to undergo open biopsy, unless their individual case warrants closed biopsy, which is done under general anesthesia. The risks of general anesthesia usually outweigh the risks of a closed biopsy. Be sure to talk with your healthcare provider if you are worried.

How do I get ready for a kidney biopsy?

The following steps will usually be necessary:

Your healthcare provider will tell you about the procedure and can ask questions.
You will be asked to sign a consent form that gives your permission to do the kidney biopsy. Read the form carefully and ask questions if something is not clear.
Your healthcare provider may do a physical exam to be sure you are in otherwise good health. You may have blood tests or other diagnostic tests. Typically, blood platelet count is evaluated to ensure that the blood will clot properly after the procedure. A low blood platelet count may indicate that you have a disorder that makes a biopsy inadvisable. However, follow your healthcare provider's specific advise.
Tell your healthcare provider if you are sensitive to or are allergic to any medicines, latex, tape, and anesthesia.
Tell your healthcare provider of all medicines (prescribed and over-the-counter) and herbal supplements that you are taking.
Tell your healthcare provider if you have a history of bleeding disorders or if you are taking any anticoagulant (blood-thinning) medicines, aspirin, or other medicines that affect blood clotting. You may need to stop these medicines before the day of the procedure. As a general guide, aspirin is stopped 10 days before the procedure. Anticoagulants (e.g. warfarin, heparin, etc) and nonsteroidal anti-inflammatory drugs (e.g. ibuprofen) must also be stopped. Follow your healthcare provider's specific advise on stopping these medications.
If you are pregnant or think you might be, tell your healthcare provider before the procedure.
You may be asked to fast before the biopsy, generally after midnight or at least 6 hours before getting anesthetic or sedatives. Your healthcare team will give you specific instructions.
You may get a sedative before the procedure to help you relax. Because the sedative may make you drowsy, you will need to arrange for someone to drive you home.
Based on your medical condition, your healthcare team may request other specific preparation.

What happens during a kidney biopsy procedure?

A kidney biopsy may be done on an outpatient basis or in a hospital. It may be done in a procedure room, in a hospital bed, or in the radiology department. Procedures may vary depending on your condition and your healthcare provider’s practices.

Generally, a kidney needle biopsy follows this process:

You will remove your clothing and put on a hospital gown.
An intravenous (IV) line may be started in your arm or hand.
You will lie on your stomach so that the healthcare provider can easily reach the kidney. A pillow may be used to hold you in the right position. If you have a transplanted kidney, you will lie on your back.
The skin over the biopsy site will be cleaned with an antiseptic solution.
You will feel a needle stick when the local anesthetic is injected. This may cause a brief stinging sensation.
You will need to lie still during the procedure.
Ultrasound or X-ray may be used to guide the needle into the kidney. This is usually a spring-loaded biopsy needle.
You will be asked to breathe in and hold your breath while the healthcare provider inserts the biopsy needle into the kidney. This prevents movement of the diaphragm, which may interfere with the placement of the biopsy needle.
You may feel discomfort or pressure when the healthcare provider takes the sample. The needle removes about 5 to 15 glomeruli.
There may be more than one puncture if the healthcare provider needs more than one tissue sample. If so, the same puncture process will be repeated. Sometimes, a third sample may be required.
After the core tissue samples are extracted, and the needle is withdrawn, firm pressure will be applied to the biopsy site to stop bleeding.
A sterile bandage or dressing will be applied.
The kidney tissue sample will be sent to the lab for testing.
Talk with your healthcare provider about what you will have during your kidney biopsy.

What happens after the kidney biopsy?

Your recovery will vary depending on the type of procedure done and your healthcare provider's practices. You may be taken to the recovery room and watched closely as the anesthesia wears off. Once your blood pressure, pulse, and breathing are stable and you are alert, you may be taken to a hospital room or discharged to your home.

You will be asked to lie on your back for several hours (usually 8-24 hours, depending on your specific situation). A nurse will check your urine for signs of bleeding. You may have blood tests to check for internal bleeding. You may be discharged later the same day or the next day. If you had a sedative or anesthetic, plan to have someone drive you home.

Bright red (arterial) blood in the urine (hematuria) may be seen for the first 24 hours. If blood is seen in the urine after 24 hours, further care may be required to stop the bleeding.

The biopsy site may be tender or sore for several days after the biopsy. Take a pain reliever for soreness as advised by your healthcare team. Many people experience muscle aches and general soreness during recovery. You may need to avoid aspirin or certain other pain medicines that may raise the chance of bleeding. Be sure to take only recommended medicines.

Contact your healthcare team and report any of the following:

Blood in your urine after the first 24 hours
Inability to urinate
Fever and/or chills
Redness, swelling, or bleeding or other drainage from the biopsy site
Increased pain around the biopsy site or elsewhere
Feeling faint

You may get back to your usual diet unless told otherwise. Your healthcare team may ask you to rest for a day or two. You will need to avoid strenuous physical activity for several days. Do not do any type of “bouncing" activities, such as jogging, aerobics, playing tennis, or horseback riding for a couple of weeks to prevent bleeding of the biopsy site.

Your healthcare provider may give you other instructions after the procedure, depending on your situation.

Reference(s)
1). E-medicine Medscape: Renal Biopsy. Available online: https://emedicine.medscape.com/article/2093338
2). Johns Hopkins Medicine: Kidney Biopsy. Available online: https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/kidney-biopsy
3). US National Institutes of Health: Kidney Biopsy. Available online: https://www.niddk.nih.gov/health-information/diagnostic-tests/kidney-biopsy