The kidneys are the specialized organs that filter and purify the blood by removing excess water, salts and waste products.
A kidney biopsy involves taking one or more tissue samples of the kidney for clinical tests. This can be useful in diagnosis where other methods such as blood and urine tests, imaging and physical exams are not. In most cases, It takes 3-5 days to get the full biopsy results from the pathologist however it might be possible to receive a partial or full report within 24 hours or less.
Methods of Biopsy
A kidney biopsy may be taken in one of two ways:
Percutaneous biopsy: a needle placed through the skin (percutaneously) that lies over the kidney and guided to the right place in the kidney – this can be done using ultrasound or CT imaging. The skin is cleaned and marked at the biopsy site which is usually the lower pole of the kidney. A local anesthetic is used to numb the needle insertion area and the patient must take in a deep breath and hold it for approximately 45 seconds or less as the needle is inserted. The patient must also stay still until the kidney sample is taken. Finally, the needle is removed and a bandage is placed over the puncture site.
Open biopsy: the kidney sample is directly obtained from the kidney during surgery and sent to a pathologist for analysis. This form of biopsy is suggested instead of percutaneous for some patients who may have a history of bleeding problems.
Purpose of Biopsy
Specific reasons to do a kidney biopsy include:
- Urine abnormalities - blood in the urine (hematuria) and protein in the urine (proteinuria)
- Abnormal blood test results such as high creatine levels (indicating kidney dysfunction thus increased waste products in the blood)
- Acute or chronic kidney disease/renal failure of unknown cause
- Persistent glomerular hematuria
- Systemic diseases with renal involvement
- Renal allograft dysfunction.
A kidney biopsy may also help to:
- Monitor tegression (or in some cases, progression) of a disease due to treatment
- Show an untreatable problem but that can be slowed down by other therapy.
- Identify the extent of permanent damage in the kidney.
- Decide on further treatment when a transplanted kidney is not working well
- Find a kidney tumor
Before the test
The patient must inform their doctor of any allergies they have and medicines they require. If the patient takes blood thinning medicines (Warfarin, Aspirin, Clopidogrel) then these are usually stopped a week prior to the procedure as a precaution to reduce the chance of bleeding during and following the biopsy. The patient must also avoid food and fluid for eight hours before the biopsy.
After the test
The patient may require bedrest for 12-24 hours after the biopsy. Remaining still in bed helps the biopsy site heal. It will also reduce the chance of bleeding – this is the main complication and in order to look for any signs of internal bleeding the patient will have their blood pressure and pulse checked. Blood tests are also done.
For two weeks after the biopsy strenuous activities should be avoided – these include contact sports, and sexual intercourse.
A doctor should also be informed if the patient experiences:
- Worsening pain, bleeding, swelling or redness in the biopsy site
- Fever and/or chills
- Faintness and dizziness
- Bloody urine for more than 24 hours after the biopsy
- Inability to urinate