A renal biopsy is the removal of a small piece of kidney tissue for laboratory examination.

Your doctor may order a kidney biopsy if you have an unexplained drop in kidney function, persistent blood in the urine, or protein in the urine. The test is sometimes used to evaluate a transplanted kidney.

There are many ways to perform a kidney biopsy. The most common uses ultrasound guidance. This means the doctor uses an ultrasound image to locate the proper area in your kidney. The biopsy is done in the hospital, usually in the radiology suite. Your doctor will go over the procedure, benefits, and risks in great detail.

You will lie face down for at least 20 - 30 minutes. A towel may be placed under your upper abdomen so you remain in the correct position. Ultrasound will be used to find the proper biopsy site. The health care provider will then inject local numbing medicine (anesthetic) under the skin near the area.

The health care provider makes a tiny cut in the skin and inserts a biopsy needle into the area and to the surface of the kidney. You will be asked to take and hold a deep breath as the needle is introduced into the kidney. If the health care provider is not using direct ultrasound guidance, you may be asked to take deep breaths to verify the needle is in place.

The biopsy needle is then withdrawn, and pressure is applied to the biopsy site to stop the bleeding. The needle may need to be inserted again (possibly several times) before enough tissue is collected. After the procedure, a bandage is applied to the biopsy site.

You will need to stay in bed for 6 - 8 hours after the procedure and will remain in the hospital for at least 12 hours. The health care team will give you pain medicines and fluids by mouth or a vein. Your urine will be checked for excessive bleeding. (A little bleeding usually occurs.) Blood counts and vital signs are monitored.

Kidney biopsies may also be done using 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 transjugular biopsy. In some cases, your doctor may recommend a surgical biopsy. Although surgical biopsies have traditionally required a 3 to 5 inch cut, they can often be done laparoscopically, which uses smaller surgical cuts. Surgical biopsies involve a longer recovery than a simpler needle biopsy.

Tell your doctor if you are pregnant or if you have any drug allergies or bleeding problems. Make sure the health care team knows what medications you are taking.

You may be told to avoid foods or fluids before the test.

The amount of pain during and after the procedure depends on the patient. Because a local anesthetic is used, discomfort during the procedure is usually minimal. The anesthetic may burn or sting when first injected. After the procedure, the area may feel tender or sore for a few days.

You may see bright, red blood in the urine the first 24 hours after the test. If the bleeding lasts longer, tell your health care provider.