Kidney biopsies are usually done in a hospital. The patient is fully awake with light sedation. A local anesthetic is given before the needle is inserted.
Patients lie on their stomachs to position the kidneys near the surface of their backs. Patients who have a transplanted kidney lie on their backs. The doctor marks the entry site, cleans the area, and injects a local painkiller. For a biopsy using a needle inserted through the skin, the doctor uses a locating needle and x-ray or ultrasound equipment to find the kidney and then a collecting needle to gather the tissue. Patients are asked to hold their breath as the doctor uses a spring-loaded instrument to insert the biopsy needle and collect the tissue, usually for about 30 seconds or a little longer for each insertion. The spring-loaded instrument makes a sharp clicking noise that can be startling to patients. The doctor may need to insert the needle three or four times to collect the needed samples.
The kidneys filter wastes and extra fluid from the blood and direct them to the bladder as urine.
The entire procedure usually takes about an hour, including time to locate the kidney, clean the biopsy site, inject the local painkiller, and collect the tissue samples.
Patients who are prone to bleeding problems should not have a biopsy through the skin. These patients may still undergo a kidney biopsy through an open operation in which the surgeon makes an incision and can see the kidney to collect tissue samples.