A renal biopsy is a procedure in which a piece of tissue is extracted from a kidney to help diagnose a kidney disorder. There are two kidneys; located in the back of the abdominal cavity, they help to balance water, salts and minerals in the blood; filter waste products from the blood; and produce urine.
Reasons for Renal Biopsy
Renal biopsies are performed for the following reasons:
- Investigate possible kidney disease
- Monitor existing kidney disease or treatment
- Follow up on a kidney transplant
- Examine renal tissue as a follow-up to abnormalities seen on an imaging test
Considerations for a Renal Biopsy
Although renal biopsies are effective tools for diagnosing the presence or extent of kidney disease, there are problems associated with their use. One problem is that they produce false-negative results. Another is that they cannot be performed if kidney cancer is suspected, because the biopsies themselves can cause the spread of malignant cells. In the case of a known malignancy, removal of the tumor, or removal of the kidney (nephrectomy), is recommended.
The Renal Biopsy Procedure
A renal biopsy is performed in one of several ways. However the biopsy is performed, the patient is hospitalized overnight. Either general or spinal anesthesia is used.
During open surgery, a fairly large incision is made through the back or side, and a piece of kidney tissue is removed. It is performed when a large piece of tissue, such as a tumor, needs to be removed. It is also recommended when a patient has only one working kidney, because it reduces the chances of injury to that kidney.
Laparoscopic surgery is minimally invasive, requiring only small incisions that result in little scarring and pain, and a short recovery. It does not, however, provide a clear visual field of the area, which open surgery does.
A ureteroscopy is performed if there is a mass in the renal pelvis or ureter. A long, thin tube called a ureteroscope is used to look inside the ureter and the lower part of the kidney. Once the mass is located, the biopsy is done through the ureteroscope.
A needle biopsy of the kidney is performed under local anesthetic. The surgeon uses either a CT scan or ultrasound technology to guide the needle that extracts a tissue sample.
Results of a Renal Biopsy
After a renal biopsy, tissue samples are sent to a pathology lab for testing. Abnormal results of a renal biopsy indicate can indicate the following:
- Poor bloodflow through the kidney
- Connective tissue disease, such as lupus
- Kidney-transplant rejection
- Malignant tumor
Risks of a Renal Biopsy
In rare instances, there are complications from a renal biopsy. The most common of these is excessive blood in the urine (hematuria), but this usually clears up within a few days. Rarely, an arteriovenous fistula, or abnormal connection between blood vessels, occurs, though it almost never causes a problem, and usually heals on its own. It is also possible for a hematoma (collection of blood) around the kidney to become infected; it is treated with antibiotics and surgical drainage. A large hematoma can also cause high blood pressure.
In addition to the risks specific to renal biopsy, the risks of any surgical procedure include the following:
- Excessive bleeding
- Blood clots
- Adverse reactions to anesthesia or medications
- Postsurgical infection
- Damage to adjacent organs
- Breathing problems
- Hernia at the incision site
Recovery from a Renal Biopsy
Recovery from a renal biopsy is generally uneventful. The patient should expect to feel pain, for which medication will be prescribed. Postsurgical pain usually lasts only a few hours. The patient is required to say in bed for 6 to 8 hours after surgery, and remains in the hospital for at least 12 hours. Intravenous fluids and pain medications are administered, and blood counts and vital signs are monitored.