What is a Renal (Kidney) Biopsy?
A biopsy is the removal of very small pieces of tissue from a body organ, that a pathologist doctor may examine under the microscope to identify various types of disease.
In the case of kidney diseases, there are two general reasons for doing a kidney biopsy. When blood or urine tests indicate that the kidneys are not functioning properly, a biopsy is done of a randomly chosen part of one kidney, assuming that all parts of both kidneys are equally affected. On the other hand, there may be a lump or mass in one kidney which may require a biopsy. The information gained by having a pathologist examine renal tissue is used to name the disease (diagnosis) and determine appropriate treatment.
How should I prepare?
You may be instructed not to eat or drink for several hours before the procedure. You will be instructed not to take blood thinners or aspirin for a specific number of days before a biopsy. However, you may take your usual medications with sips of water. If you are diabetic and take insulin, discuss with your doctor whether to adjust your insulin dose.
Inform your doctor of all medications you are taking, and any allergies to medications or to latex. Women should always inform their physician if there is a possibility they may be pregnant.
You may want to have a responsible friend or relative to accompany you and drive you home afterward. This will be required if sedation is to be given. A renal biopsy done because of poor kidney function will usually require an overnight stay in the hospital.
How is the procedure performed?
Most often, a kidney biopsy is done using ultrasound to guide the placement of the local anesthesia and the biopsy needle. Occasionally, CT guidance is required, particularly if the biopsy is being done for a kidney mass. The patient is usually lying flat, usually face down. A safe path is found, the skin is cleansed with antiseptic, and local anesthetic is infiltrated along the path of the biopsy needle. A single needle is placed up to the kidney, and then samples are removed through that needle up to four times, to get enough tissue for the pathologist to analyze. The needle is then removed. The patient is monitored while lying flat after the procedure for three to four hours in the case of a kidney mass, or overnight in the case of poor kidney function.
What will I experience during and after the procedure and when will I get my results?
You will be asked to remove clothing above the waist and wear a gown. You will be positioned on a stretcher, or on a CT table, and a scan is done. The skin is cleansed and a local anesthetic given, which may sting briefly. Placement of the biopsy needle should then be painless. You will have to be motionless for up to 30 minutes, breathing normally. You will be asked to hold your breath briefly. After the needle is removed and a sterile dressing applied, you will be monitored by our nursing staff. Inform the nurse if you develop any pain in your back or abdomen after the biopsy.
Avoid strenuous exertion or distant travel for 24 hours. Signs of internal bleeding from a kidney biopsy include new abdominal pain after the biopsy, feeling faint, or rapid pulse rate. If you develop these symptoms, go to the nearest emergency room and inform the emergency physician of your recent kidney biopsy.
The pathology results will be available in about three to four business days after the procedure. They will be available to your physician. Please contact your referring physician if you have not received these results after one week.
What are the benefits and risks?
Needle biopsy is a reliable and accurate way to determine the nature of kidney disease, or whether a kidney mass is benign or malignant, and to decide what course of treatment is necessary. Needle biopsy is safer and easier to tolerate than surgical biopsy, and the recovery time is brief.
There are some risks: About 5 percent (one out of twenty) of patients who undergo a renal biopsy for poor kidney function will have significant internal bleeding that requires a transfusion. Rarely, another procedure is required if bleeding continues. When a biopsy is done for a kidney mass, severe bleeding is less common (about 2 percent of biopsies).
In a very small percentage of biopsies, the tissue obtained may not be sufficient to give a diagnosis, usually a biopsy done on a small kidney mass. In that case a biopsy may be repeated.
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