A kidney biopsy is done to remove a small piece of kidney tissue to examine under a microscope to find out what is causing the kidney disease and its severity so appropriate treatment plans are chosen by your kidney doctor.

Most often this is done under direct picturing and guidance of an ultrasound or CT scan by inserting a thin needle through the skin of the back to the kidney for obtaining a small sample tissue.

Why it's done

A kidney biopsy may be done to:

• Diagnose a kidney disease that can't otherwise be identified by history and blood tests
• Help develop treatment plans and appropriate medications based on the kidney's tissue findings
• Determine how advanced the kidney disease is and how quickly it is progressing
• Determine the extent of damage from kidney disease or another disease attacking the kidney
• Evaluate how well treatment for kidney disease is working
• Monitor the health of a transplanted kidney or find out why a transplanted kidney isn't working properly

Your kidney doctor may recommend a kidney biopsy based on the results of blood or urine tests that show:

• Blood in the urine (hematuria) that comes from the kidney
• Protein in the urine (proteinuria) that's excessive and over a limit, rising or accompanied by other signs of kidney disease
• Problems with kidney function, leading to excessive waste products in the blood

Kidney biopsy is not necessarily needed in everyone with these problems. The decision is usually made between you and your kidney doctor based on your signs and symptoms, test results, and overall health.

Risks

In general, kidney biopsy is a safe procedure. Possible risks include:

• Bleeding.　The most common complication of a kidney biopsy is a collection of blood around the kidney (hematoma) and sometimes blood in the urine (hematuria). The hematoma is usually self-contained and the doctors monitor it for no expansion. The blood in the urine usually stops within a few days. Bleeding that's serious enough to require a blood transfusion affects a very small percentage of people who have a kidney biopsy and you have to agree to it before undergoing biopsy. Rarely, further interventions and even surgery is needed to control ongoing bleeding.
• Pain.　Pain at the biopsy site is common after a kidney biopsy, but it usually lasts only a few hours.
• Arteriovenous fistula.　If the biopsy needle accidentally damages the walls of a nearby artery and vein, an abnormal connection (fistula) can form between the two blood vessels. This type of fistula usually causes no symptoms and closes on its own.
• Others.　Rarely, a collection of blood (hematoma) around the kidney becomes infected. This complication is treated with antibiotics and surgical drainage. Another uncommon risk is development of high blood pressure related to a large hematoma.

How you prepare

Your kidney doctor will talk about what to expect during a kidney biopsy. This is a good time to ask questions about the procedure and make sure you understand the benefits and risks.

Medications

When you meet with your doctor, bring a list of all medications you take, including over-the-counter medications, vitamins and herbal supplements. Before your kidney biopsy, you'll be asked to take your blood pressure medications but stop water pills and taking medications and supplements that can increase the risk of bleeding. These include:

• Blood-thinning medications (anticoagulants), such as heparin, warfarin (Coumadin, Jantoven), rivaroxaban (Xarelto), apixaban (Eliquis), dabigatran (Pradaxa) or enoxaparin (Lovenox)
• Aspirin
• Ibuprofen (Advil, Motrin IB, others) and other nonsteroidal anti-inflammatory drugs (Aleve, Narosyn, NSAIDs)
• Certain dietary supplements that increase risk of bleeding, such as omega-3 fatty acids

Generally, these medications will be stopped several days before the procedure and may be resumed several days after the procedure. Your doctor or nurse will let you know when to stop taking these medications and supplements, and for how long.

Blood and urine samples

Before your biopsy, you'll have blood drawn and provide a urine sample to make sure you don't have an infection or another condition that would make the biopsy risky.

Diet

You may be asked not to drink or eat for eight hours before the kidney biopsy.

What to Expect:

A kidney biopsy is done at a hospital or outpatient center. Usually an IV will be placed before the procedure starts for giving fluids or medications.

During the procedure

During the procedure, you'll be sedated but awake and able to follow instructions. The physician will choose which kidney to biopsy, right or left. You lie on your abdomen or your side, depending on which position allows best access to the kidney which is being biopsied. For biopsy of a transplanted kidney, most people lie on their backs as this kidney is closer to the front of abdomen.

A kidney biopsy takes about an hour and includes these steps:

• Either with an ultrasound or CT scan, the doctor identifies exactly where to insert the biopsy needle.
• You are given a medication to relax through the IV prior to the procedure.
• Your doctor marks your skin, cleans the area with an antiseptic and applies a numbing medication (local anesthetic like lidocaine).
• If you experience any pain not controlled by the numbing medicine, your doctor may give you some pain medication through your IV during the procedure.
• Your doctor makes a small incision where the needle will go in and uses the ultrasound device or CT scan to guide the needle into your kidney.
• You may be asked to hold your breath as your doctor collects a kidney tissue sample. You may feel a "pop" or pressure and hear a clicking noise.
• To get enough tissue sample for best analysis, your doctor may need to insert the needle few times — often through the same incision.
• After enough tissue is sampled the doctor removes the needle and places a small bandage on the incision and checks to make sure there is no bleeding.

Other kidney biopsy procedures

The above kidney biopsy may not be an option for some people. If you have a history of bleeding problems, have a blood-clotting disorder or have only one kidney, your doctor may consider other types of biopsy like laparoscopic biopsy.

In this procedure, the surgeon makes a small incision and inserts a thin, lighted tube with a video camera at its tip (laparoscope) through your back. This tool allows the surgeon to view your kidney on a video screen and remove tissue samples.

After the procedure

After the kidney biopsy, you can expect to:

• Rest quietly for several hours in a recovery room where your blood pressure, pulse and breathing will be monitored.
• Have your urine examined and complete blood count test done to check for bleeding and other complications.
• Receive written instructions about your recovery.
• Feel some soreness or pain at the biopsy site for a few hours. You'll be given medications to relieve pain.

Most people can leave the hospital or outpatient center the same day. You may need to rest in bed for 12 to 24 hours after the biopsy, as directed by your doctor. You will receive instructions about any activity restrictions, such as avoiding heavy lifting and strenuous exercise, jogging and jumping.

Call your doctor if you experience:

• Significant bright red blood or clots in your urine more than 24 hours after the kidney biopsy
• Inability to pass urine
• Worsening pain at the biopsy site
• Fever over 100.4 ^oF (38 ^oC)
• Faintness, dizziness or weakness

Results:

The tissue sample is sent to an outside pathology lab that specializes in looking at kidney tissue. It may take 7-10 days to get your biopsy report from the pathology lab. In urgent situations, a partial report may be available to your kidney doctor sooner. At a follow-up visit, your kidney doctor will discuss the results with you. The biopsy results may further explain what's causing your kidney disease, or the results may be used to change or adjust your treatment plan.