Kidney biopsy

This page was reviewed under our medical and editorial policy by

Farshid Sadeghi, MD, Medical Director of Genitourinary Center, CTCA Phoenix.

This page was updated on May 20, 2022.

A biopsy is often used to diagnose cancer. During a biopsy, a small sample of tissue is taken from the area in question and sent to a laboratory for further investigation under a microscope. Kidney cancer doesn’t always require a biopsy. Sometimes imaging tests such as a computed tomography (CT) scan, magnetic resonance imaging (MRI) and ultrasound may be sufficient to identify kidney tumors and determine whether they’re benign (noncancerous) or malignant (cancerous).

Still, your doctor may order a kidney biopsy if:

  • You have small, slow-growing tumors being monitored
  • Your imaging tests are not as conclusive as your doctors would like
  • You’re a candidate for treatments other than surgery
  • You’ve undergone treatment, and your doctors want to see how well you’re doing or if the cancer has returned

A kidney biopsy may also be ordered to evaluate the following conditions.

  • Hematuria: Blood in the urine may be a sign of a problem with kidney function. A biopsy may help diagnose hematuria.
  • Albuminuria: Albumin is a protein. Albuminuria happens when you have an abnormal amount of protein in your urine. A kidney biopsy may be needed to diagnose this issue.
  • Changes in kidney function: A biopsy may be ordered to determine why your kidneys aren’t functioning properly and waste products are building up in your blood.

If your doctors suspect that cancer has spread to other tissue, they may perform a biopsy of that site rather than of your kidney.

Who performs a kidney biopsy

Your kidney biopsy may be performed at a hospital or an outpatient surgery center.

A number of specialists may perform the biopsy, including:

  • Nephrologist, who specializes in conditions related to the kidneys
  • Urologist, who specializes in diseases of the urinary tract and male reproductive system
  • Transplant surgeon, who specializes in performing organ transplants
  • Interventional radiologist, who performs procedures with the aid of imaging equipment

How a kidney biopsy is performed

Your care team has several options:

  • Percutaneous, which means through the skin, typically with a needle
  • Open biopsy, a rare procedure that requires an incision in the abdomen to give the doctor access to the kidney

In either case, the sample that’s taken is sent to a lab where it’s examined by a pathologist.

During a percutaneous biopsy

  • You’ll likely be asked to lie on your stomach on the examination table. A firm pillow or sandbag may be placed under your stomach to provide support and push your kidneys closer to your skin.
  • You’ll receive a sedative through an intravenous (IV) line.
  • Your health care team uses an ultrasound or X-ray to locate your kidney. You may be given a contrast material through your veins to make the kidney and important blood vessels light up and easier to see.
  • Your doctor may mark your skin once the spot is identified. Your skin is then sterilized.
  • You’ll be asked to stay still and hold your breath as the doctor puts the needle through your skin. You may feel some pressure or a “pop” where the needle is inserted in your kidney.
  • If the doctor isn’t using ultrasound to guide the needle insertion, you may be asked to breathe in and out with deep breaths. This helps the doctor know that the needle was properly placed.
  • Your doctor may need to pass the needle through your skin up to four times to be sure a large enough sample is taken. Each time you may be asked to hold your breath.
  • Pressure is applied to the site where the needle was inserted to stop any bleeding.

A percutaneous biopsy should take about an hour. The biopsy alone may take about 15 minutes to a half-hour.

During an open biopsy

  • You’re given general anesthesia, so you don’t feel anything during the procedure.
  • Your surgeon makes a small incision above your kidney.
  • Your surgeon identifies the area of your kidney that’s of concern and removes a small sample.
  • Your surgeon closes the incision with sutures.

Afterward, you’ll likely be given medicine to help alleviate any pain from the surgery, and you also may be given fluids by mouth or an IV.

The staff will monitor your urine for heavy bleeding.

How to prepare for a kidney biopsy

  • Speak with your doctor about your procedure, why you’re having it, and what the results could mean. This may help relieve stress and make you feel prepared.
  • Arrange for a ride to and from your procedure. You can’t drive home after general anesthesia.
  • Tell your doctor about any medications you’re taking, whether they’ve been prescribed to you or you bought them over the counter. Include any vitamins and supplements. Ask which, if any, you should take before or the day of your procedure. Be sure to mention if you’re taking blood thinners and ask when to stop them. You may need to stop taking blood thinners up to two weeks before your biopsy.
  • Inform your doctor of any allergies to medications or foods.
  • Don’t eat or drink for at least eight hours before your procedure is scheduled.
  • You may take a bath or shower before the biopsy, but don’t use lotion, perfume or deodorant. Avoid nail polish as well.
  • Leave jewelry at home, including piercings.
  • Arrive 90 to 120 minutes before you’re scheduled so you have time to fill out the necessary paperwork, undergo needed blood tests and receive IV fluids and sedatives. Your blood and urine will be tested for bleeding issues or high blood potassium that would make it too risky for you to undergo a kidney biopsy.

Post-biopsy care

Under observation, you should remain lying on your back for four to six hours after the procedure. You may be in the hospital afterward for a minimum of 12 hours. You should be allowed to leave once your blood pressure and pulse are stable.

  • Follow the directions you’re given for the care of your wound. You may need to keep your bandage on for at least one to two days.
  • Expect some soreness where the needle was inserted or where your incision was made for the next couple of days. Don’t take aspirin to relieve the pain, as it acts as a blood thinner and may cause bleeding.
  • Don’t lift objects that weigh more than 10 pounds for at least two weeks after your biopsy. Avoid activities that may injure your kidney (such as contact sports) until you’re fully recovered. Your doctor should tell you when you may resume the physical activities you did before.
  • Moving may help your recovery. Start with walking, going a little longer and farther each day. Moving helps your circulation.
  • Expect to hear from your doctor with the results in three to five days, but it may be sooner.
  • You should be able to resume your normal diet.

Fuhrman grade tumors

The pathologist who examines your tissue sample cells will grade it as a 1, 2, 3 or 4 using the Fuhrman system for kidney cancer. According to this system, the more abnormal the cells, the higher the grade.

The grade is used to help determine the most appropriate treatment for your cancer.

Risks of kidney biopsy

While risks are rare, a kidney biopsy is a surgical procedure, which means there’s a possibility of complications. Some risks include:

  • Damaged blood vessel: Surgery may be needed to fix it.
  • Serious bleeding: You may need a transfusion as a result of blood loss.
  • Infection: As with any surgery, infection is always a risk, but it’s rare when undergoing a kidney biopsy. If you develop an infection, you’ll be given antibiotics to treat it.

Because doctors only take a tiny sample of the kidney, it’s possible they miss the actual cancer—that the area they take the sample from doesn’t have cancer. It’s also possible for the biopsy needle to spread the cancer.

If you have high blood pressure (greater than 140/90), you’re at greater risk of complications during the procedure. Your doctor may try to control your blood pressure with medications before performing a biopsy.

Discuss the risks and benefits with your care team before you undergo a kidney biopsy.

When to call the doctor

You should call your doctor immediately if you have any of these issues after your kidney biopsy:

  • Inability to urinate
  • Frequent urination and/or constant urge to go
  • Burning sensation when going to the bathroom
  • Dark red or brown urine
  • Blood or pus seeping from under your bandage
  • Fever
  • Faintness

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