What is a renal biopsy?
A renal biopsy is a diagnostic test that allows to know the type of disease affecting the kidneys, by removing a fragment of tissue.
The kidney diseases that are evaluated with this test are those called nephrosis, which damage both kidneys, although in an inconspicuous way at the beginning. Although nephrosis can be detected through urine analysis, in which traces of blood (microhematuria), protein (proteinuria) or cretinine appear, the analysis does not give us any indication of the type or the damage caused by the disease, nor can we know with only one analysis the treatment to be carried out. On the other hand, with a renal biopsy we can start an appropriate treatment to improve or slow down the disease.
What does it consist of?
Renal biopsy consists of extracting a fragment of tissue from the kidneys for subsequent examination under a microscope. To carry it out, the patient is punctured with a needle in one of the kidneys, a process called percutaneous renal biopsy. Only in some cases will a small surgical intervention be necessary, making a minimal incision in the lumbar area under local anesthesia, extracting a small fragment of the kidney.
In percutaneous renal biopsy, in order to select the most suitable area of the kidney, the needle is guided with ultrasound, and the patient is administered local anesthesia, holding the patient’s breath for a few seconds.
The patient must remain in the hospital for one night, resting absolutely. If there are no complications the following day, the patient will be discharged from the hospital.
Why is it performed?
The nephrologist will ask the patient to undergo a renal biopsy if there is a decrease in kidney function or if there is blood or protein in the urine. It is also performed to examine and evaluate transplanted kidneys.
Preparing for kidney biopsy
Before undergoing a kidney biopsy, the patient should inform the specialist:
- Medications you are taking, even if they are herbs or vitamin supplements.
- If you have any allergies
- If you have bleeding problems or take anticoagulant medications.
- If you are or think you may be pregnant
In addition, your doctor may advise you to stop taking solid foods or liquids before the biopsy.
How will you feel during the test?
Local anesthesia is used to perform a kidney biopsy, so pain is usually mild. However, the anesthesia stings or burns slightly when injected. After waking up the anesthetized area may feel slightly uncomfortable or tender for a few days.
It should be noted that there may be traces of bright red blood in the first 24 hours after the test.
What abnormal results mean
Abnormal results of a kidney biopsy may alert to changes in the kidney, caused by:
- Infection
- Poor blood flow through the kidney
- Connective tissue diseases, such as systemic lupus erythematosus
- Diabetes
- Kidney transplant rejection, in the case of transplant recipients