A renal biopsy is a way to obtain a sample of kidney tissue. The sample is then examined in the laboratory.
There are many ways of performing the biopsy. The most common is under ultrasound guidance. Biopsies are also performed with CT scan guidance. Under some circumstances, the biopsy may be performed by running the biopsy catheter through one of the neck veins -- this is called a trans-jugular biopsy.
When performing the biopsy under ultrasound guidance, the test is done in the hospital, usually in the radiology suite. Your doctor will go over the procedure, benefits, and risks in great detail.
The patient is expected to lie face down for at least 20-30 minutes. A towel may be placed under the upper abdomen to achieve an appropriate position. The kidney is located using the ultrasound, and then the health care provider will mark the biopsy site. A local anesthetic will be given to numb the skin at the biopsy site. A tiny incision is then made in the skin.
A biopsy needle will be inserted into the skin. Based on a previously determined kidney position or under direct ultrasound visualization, the needle is advanced to the surface of the kidney. The patient is then asked to take and hold a deep breath, the needle introduced into the kidney, and fired. If the physician is not using direct ultrasound guidance, he may ask the patient to take deep breaths to verify needle "embedment" before firing.
The biopsy needle is then withdrawn and pressure is applied to the biopsy site to stop the bleeding. Several passes may be required before an adequate amount of tissue is collected. After the procedure, a bandage is applied to the biopsy site.
The patient is requested to remain in bed for 6-8 hours after the procedure. Pain medicines are prescribed. Oral or IV fluids are administered and urine monitored for excessive hemorrhage. (A little bleeding usually occurs). Blood counts and vital signs are monitored. The patient is observed in the hospital for a day.
Inform the doctor of any drug allergies you may have, which medications you are taking, if you have bleeding problems, and if you are pregnant. You must sign a consent form. You may be restricted from food or fluid before the test.
When the local anesthetic is injected, there will be a prick and a mild stinging. As the biopsy is done, there will be an aching feeling. After the test there may be muscle soreness. You may see bright, red blood in the urine the first 24 hours after the test. If the bleeding lasts longer, inform the health care provider.
A normal value is when the kidney tissue shows normal structure.
An abnormal value is when the test shows changes in the kidney tissue caused by infection, poor blood flow through the kidney, signs of connective tissue diseases such as systemic lupus erythematosus, or other diseases that may be affecting the kidney.
For transplant patients, there may be signs of transplant rejection.
Additional conditions under which the test may be performed:
- Acute nephritic syndrome
- Acute tubular necrosis
- Alport syndrome
- Atheroembolic renal disease
- Chronic glomerulonephritis
- Complicated urinary tract infection
- Diabetic nephropathy
- Focal segmental glomerulosclerosis
- Goodpasture's syndrome
- IgA nephropathy (Berger's disease)
- Interstitial nephritis
- Lupus nephritis
- Medullary cystic disease
- Membranoproliferative GN I
- Membranoproliferative GN II
- Membranous nephropathy
- Minimal change disease
- Nephrotic syndrome
- Post-streptococcal GN
- Rapidly progressive glomerulonephritis
The main risk is bleeding from the kidney which, in 1% of patients, may require a blood transfusion. There is a very minimal chance of infection. There can be bleeding into the muscle, which might cause soreness.
For 2 weeks after the test, avoid strenuous activities and lifting heavy objects. Sometimes a repeat biopsy is needed.
Reviewed By: Charles Silberberg, DO, Private Practice specializing in Nephrology, Affiliated with New York Medical College, Division of Nephrology, Valhalla, NY. Review provided by VeriMed Healthcare Network.