A doctor inserts a long needle through your skin and into the kidney to obtain a tissue sample for microscopic examination. Fluoroscopy, ultrasonography, or CT scanning may be used to guide placement of the needle. Occasionally, an open renal biopsy—which accesses the kidney surgically through a small incision—is performed instead.
Purpose of the Renal Biopsy
- To identify the reason for poor kidney function
- To diagnose a suspected kidney (renal) disorder (for example, after finding blood or protein in the urine) or unexplained kidney dysfunction
- To monitor the effectiveness of treatment for renal disease
- To evaluate a transplanted kidney for signs of organ rejection, as well as to determine the appropriate dose of immunosuppressive drugs
- To detect a kidney malignancy in patients who are unable to undergo surgery
Who Performs It
- A nephrologist assisted by a radiologist or a radiology technician
- People who have serious bleeding disorders, hydronephrosis (collection of urine in the renal pelvis due to obstructed outflow), urinary tract infections, severe hypertension, or only a single kidney are not candidates for this procedure.
- Individuals with operable kidney tumors should not undergo this procedure, since there is a risk it may disseminate tumor cells.
- Blood coagulation tests are performed to determine whether you have any bleeding abnormalities. If so, the biopsy may be canceled.
Before the Renal Biopsy
- Report to your doctor any medications, herbs, or supplements you are taking. You may be advised to discontinue certain drugs (including nonsteroidal anti-inflammatory drugs, such as aspirin or naproxen) before the test because they can interfere with blood clotting.
- Inform your doctor if you are allergic to any medications, anesthetic agents, latex or tape.
- Restrict your intake of food and fluids for 8 hours before the test.
- If you are anxious about undergoing this procedure, your doctor may prescribe a sedative to relax you.
- Inform your doctor if you are pregnant or suspect that you may be pregnant.
- You will be instructed to empty your bladder just before the test.
What You Experience
- You will lie face down on an examining table with a pillow or sandbag under your abdomen to straighten your spine.
- The skin over your kidney is cleansed with an antiseptic to help prevent infection, and a local anesthetic is injected to numb the area (you may still feel a pinching pain when the biopsy is taken).
- While you hold your breath and remain still to stop kidney motion, the doctor inserts a thin biopsy needle and obtains a specimen, using fluoroscopy, ultrasound, or CT scanning to visualize the kidney. (A small finder needle may be used to correctly locate the kidney prior to using the longer biopsy needle.)
- The doctor may repeat this procedure a few times until an adequate specimen is obtained, and the needle is withdrawn.
- The procedure may take as little as 15 or 20 minutes once the kidney is well visualized.
Risks and Complications
- Many patients experience back pain and some urinary tract bleeding in the first 24 hours after the procedure.
- Possible serious complications include infection, major blood loss and need for transfusion, displacement of the kidney, bleeding into the muscle which might cause soreness and, rarely, loss of the kidney or death.
- Rarely, the biopsy needle may inadvertently puncture another organ (such as the liver, lung, or bowel) or a blood vessel (such as the aorta or inferior vena cava).
After the Renal Biopsy
- You are positioned on your back and advised to stay in a hospital bed for 12 to 24 hours. Your vital signs are carefully monitored during this time, and the needle insertion site is checked for signs of bleeding or infection.
- Your urine is examined for blood. Some individuals have visible blood in the urine initially, but this typically subsides after 24 hours.
- You are encouraged to drink plenty of fluids after the procedure to prevent blood clot formation and urine retention. You may resume your normal diet.
- Your doctor may prescribe a pain reliever for any back pain.
- Upon returning home, you should avoid strenuous activities, exercise and lifting heavy objects for at least 2 weeks to prevent possible bleeding.
- Call your doctor if you experience symptoms of kidney hemorrhage (such as worsening back, flank, or shoulder pain or lightheadedness) or urinary tract infection (a fever or burning on urination).
- A pathologist examines the kidney specimen under a microscope for changes that indicate a specific kidney disorder, malignancy, or transplant rejection.
- This test usually results in a definitive diagnosis. Appropriate treatment will be initiated, depending on the specific problem.
The Johns Hopkins Consumer Guide to Medical Tests
Simeon Margolis, M.D., Ph.D., Medical Editor
Updated by Remedy Health Media