What is a kidney biopsy?
A kidney biopsy is a test doctors use to help diagnose kidney disease. During this test, a doctor takes a sample of kidney tissue and sends it to a laboratory for examination.
Most kidney biopsies are performed at a hospital or outpatient clinic, either in radiology or a procedure room. A kidney biopsy is also called a renal (related to the kidneys) biopsy.
Why is a kidney biopsy done?
A kidney biopsy helps doctors identify the cause of kidney problems so they can treat the condition effectively. It can reveal scarring, inflammation (swelling), and protein deposits that cannot be identified with other tests, such as ultrasounds or blood and urine tests.
The test can also enable a doctor to see how well a transplanted kidney is working and monitor the progression of kidney disease.
Your doctor may recommend a kidney biopsy if you have:
- A transplanted kidney.
- Abnormal results from a blood test.
- Glomerular disease (damage to the filtering units in the kidneys) or glomerulonephritis.
- Hematuria (blood in the urine).
- Kidney disease with no known cause.
- Proteinuria (protein in the urine).
What is a transplant kidney biopsy?
While a kidney biopsy is a procedure where small samples of the kidney are removed in order to be examined by a pathologist under a microscope. A transplant kidney biopsy is done either as a screening test or to see what is happening with a kidney that is not working properly. It provides more information than can be obtained from a noninvasive procedure (ultrasound or x-ray, for example). Biopsy is considered the best option to diagnose problems with transplanted kidneys.
Why is a transplant kidney biopsy performed?
A transplant kidney biopsy is done either to screen for otherwise undetected problems with the kidney (infections for example) or when there are signs that the kidney is not working well. Kidney disease can occur anytime after the transplant, and biopsies can help with diagnosing and treating these problems. Signs of problems may include little or no urine output, fever, high blood pressure, and abnormal lab values. These could include an increasing serum creatinine level. Other signs may include blood or protein in the urine, damage to the filtering parts of the kidney; or kidney disease with no clear reason. A biopsy may detect rejection of the kidney before actual signs are seen, improving the chance of better long term outcomes.
What problems can a transplant kidney biopsy show?
The procedure can verify if the donor kidney is working well. Examples of abnormalities detected by the biopsy include rejection-both from antibodies or cells. Rejections can be rapid and aggressive or slow and subtle. Over time; damage to the kidney from the following may occur:
- Poor blood flow or scarring
- Viral or bacterial infections
- Evidence of kidney injury from certain drugs
- Evidence that a prior kidney disease has returned
- Evidence that a new kidney disease has begun (often the one that injured the original kidneys)
- Occasionally, kidney tumors or tumors from other sites in the body
Very often biopsy findings lead to changes or adjustments in treatment by your transplant doctor.
What happens during a kidney biopsy?
During a kidney biopsy, a doctor collects a sample of tissue from your kidney. Most biopsies are done through your back, although people with a transplanted kidney have the biopsy through their lower abdomen (belly).
Your doctor will use one of these methods to take the sample:
- Percutaneous biopsy: In this more common type of kidney biopsy, a doctor numbs the skin located over the kidney and inserts a needle to take a small tissue sample from the kidney. Your doctor may use ultrasound imaging to guide the needle to the best location in the kidney.
- Open biopsy: In an open biopsy, a doctor makes an incision (small cut), removes tissue from the kidney, and closes the incision with stitches. Your doctor will give you anesthesia (medicine that makes you sleep) so you do not feel pain during the procedure. This type of biopsy is rare except at the time of kidney transplant.
How do I prepare for a kidney biopsy?
Some medications can decrease blood clotting and increase the risk of bleeding during the procedure. You should stop taking these medications, including aspirin, warfarin, apixaban, ibuprofen, and other blood thinners and anti-inflammatory drugs at least one week before a kidney biopsy. Your doctor will ask about any other medicines or supplements you take and recommend any needed changes to your medication regimen.
Your doctor will take urine and blood samples before the biopsy to make sure you do not have any infections or other conditions that could cause complications. In most cases, doctors tell people not to drink or eat anything after midnight prior to the biopsy.
It’s important to take other medication as usual on the day of biopsy. Blood pressure medication should be taken to avoid high blood pressure at the time of biopsy, and medicine may be taken with sips of water.
How is the sample obtained in a transplant kidney biopsy?
There are two ways to obtain the sample during a transplant kidney biopsy. A needle can be used that will go through the skin and into the kidney. The needle then is used to collect the sample. An ultrasound image is used to help guide the needle to the correct spot. This process is called a percutaneous biopsy. The second method would be to take a sample during surgery, this is much less common. Ultrasound guided transplant kidney biopsies are most often done under local anesthesia.
Is there a reason why a transplant kidney biopsy might be delayed?
If it is suspected that a person has an infection prior to the procedure, the transplant renal biopsy may be delayed until the infection is treated. If the patient is taking strong anti-coagulation drugs for other reasons, (warfarin, for example), they would need to be stopped for several days prior to and immediately after the biopsy. The risk vs. the benefits of stopping anti-coagulation will have to be weighed by your transplant doctor.
What can I expect after a transplant kidney biopsy?
During a standard biopsy, you will be observed for 1-2 hours in the recovery area to ensure you are well, can drink fluids, and pass urine comfortably. When released from the biopsy area, you should go directly home and stay indoors overnight. The next day you can walk or drive a car as needed. It will be important to avoid strenuous activity or heavy lifting for up to another two days after the procedure. If an open biopsy is required, you will receive further instructions.
Results and Follow-Up
How will I recover from a kidney biopsy?
You’ll lie flat for several hours after the procedure while your doctor and nurses monitor you. After a native kidney biopsy, most patients spend one night in the hospital.
After a transplant kidney biopsy, most people go home the same day. You’ll need someone to give you a ride home, because you may feel drowsy from the medications.
You should expect to remain quiet and rest for about a day after the procedure.
What do the results of a kidney biopsy mean?
A kidney biopsy can reveal medical conditions that may impair kidney function, such as an immunologic disease (diseases that happen because the immune system doesn’t work properly). It can also help a doctor evaluate how well a donated kidney is working after a transplant.
The test results can help your doctor determine the most effective treatment for the kidney disease. People usually receive the results of a kidney biopsy within three to five days.
What are the complications of a kidney biopsy?
The risks of a kidney biopsy are small, but complications can occur. Some people experience bleeding after the procedure. Severe bleeding might require further treatment.
Other complications of a kidney biopsy may include:
- Inability to urinate.
- Pain at the biopsy site.
- Urine infection.
Contact your doctor if you experience complications of a kidney biopsy.
What are some of the risks of a transplant kidney biopsy?
While the risks of a biopsy are small, complications could occur. Bleeding may occur. About a third of patients have some light red color in the urine for a day or so of little consequence. About 1-3% of patients have bleeding with clots that required a bladder irrigation with a catheter to clear them. If the bleeding is severe enough, a transfusion may be needed. However, this is a very rare occurrence in less than 1% of patients. Very rarely a urine infection may occur, especially in patients with a history of frequent urine infections. Other problems to watch for include fever, pain at the site of the biopsy, dizziness, or not being able to urinate.
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