What is a Kidney Biopsy?

A kidney biopsy, also called a renal biopsy, is a medical procedure in which a small piece of tissue from the kidney is removed so that it can be examined in a laboratory. The kidneys are located low on either side of the back. They are involved in balancing the proportion of water, minerals, and salts in the blood, filtering waste, and creating urine. A biopsy may be ordered to help with a diagnosis when kidney problems are suspected.

Most often, a doctor who specializes in urology, nephrology, or radiology performs a kidney biopsy. The most common way to perform this type of biopsy is using ultrasound guidance, in which the doctor uses an ultrasound image to locate the proper area of the kidney to be biopsied. Usually the patient must lie face down on an exam table with a pillow or folded towel placed under the stomach for support and for proper placement. The doctor will begin the procedure by marking the skin over the intended entry site, cleaning the site with antiseptic soap, and giving the patient a local anesthetic in the biopsy area.

A small spot must be cut in the skin over the biopsy site to insert the needle for the biopsy, and the exact area for biopsy is located with ultrasound. Tissue is obtained through the biopsy needle, which may need to be inserted several times to obtain enough tissue. After removing the last sample, pressure is applied to the site to stop bleeding, and the area is bandaged. The entire procedure usually takes one hour or less.

After the kidney biopsy, it is normal for the patient to remain in the clinic or the hospital for eight to 24 hours, during which time blood pressure, temperature, and bleeding will be carefully monitored. Patients are usually advised to return to their normal diets, and to drink plenty of fluids to avoid dehydration. Strenuous activities or anything that might cause a bump to the kidney area should be avoided for at least two weeks following a kidney biopsy.

Several conditions can warrant a kidney biopsy, including blood in the urine, called hematuria, or excessive levels of protein in the urine, called proteinuria. A kidney biopsy may also be performed to make sure that a kidney that was transplanted is working properly, to monitor the progression of kidney disease, or to see if a particular treatment is working. In cases that kidney cancer is suspected, a biopsy may not be performed if there is a risk of spreading the cancer.