Overview of Kidney Biopsy
Percutaneous kidney biopsy (through the skin) the removal of a sample of kidney tissue for diagnosis or to evaluate the function of a transplanted kidney. A nephrologist (kidney and renal system specialist) performs the procedure on an outpatient basis, usually in the radiology department of the hospital. Preparation, biopsy, and recovery take several hours.
Kidney Biopsy Preparation
The following medications must be discontinued before biopsy to reduce bleeding:
- Aspirin (10 days before)
- Warfarin (Coumadin, Jantoven, generics), Heparin, and other anticoagulants
- Nonsteroidal anti-inflammatory drugs (e.g., ibuprofen)
Typically, blood platelet count is evaluated to ensure that the blood will clot properly after the procedure. A low blood platelet count may indicate that the patient has a disorder that makes a biopsy inadvisable.
Kidney Biopsy Procedure
Biopsy is performed on one kidney. The patient lies on his or her stomach on a firm table with cushioning under the abdomen for support and must not move during the procedure.
Once the kidney is located with ultrasound or CT scan, the biopsy site is marked over the right kidney and a local anesthetic is injected. Once the area is numb, the nephrologist uses ultrasound to view the kidneys in real time and guides a spring-loaded biopsy needle into the kidney.
The needle removes about 5 to 15 glomeruli. Two or three samples are usually required, each the size and shape of one-half inch of string. After the core tissue samples are extracted, pressure is applied to the incision to slow bleeding, and a bandage is placed on the wound.
Post Kidney Biopsy Care
The patient must lie on his or her back for 8 to 24 hours. Some nephrologists advocate a 24-hour recovery in the hospital, where the patient can be observed for complications.
The kidney contains many blood vessels and bleeds as a result of the biopsy. Bright red (arterial) blood in the urine (hematuria) may be seen for the first 24 hours. If blood is seen in the urine after 24 hours, further care may be required to stop the bleeding. Many people experience muscle aches and general soreness during recovery.
Kidney Biopsy Complications
The following complications may occur:
- Acute blood loss (in as many as 10%)
- Bleeding requiring surgery, transfusion, or kidney removal (less than 1%)
- Death (less than 1%)
- Pain lasting longer than 12 hours (in 4%)
Contraindications to Kidney Biopsy
The most common contraindication to kidney biopsy is disease:
- Bleeding disorder (e.g., inability to coagulate, platelet abnormality)
- Pyelonephritis (disease of the pelvis of the kidney)
- Shrunken kidney (i.e., as a result of disease)
Nephrologists generally consider it safe for people with only one kidney (solitary kidney) to undergo open biopsy, unless their individual case warrants closed biopsy, which is done under general anesthesia. The risks of general anesthesia usually outweigh the risks of a closed biopsy.
Other Types of Kidney Biopsy
Other types of biopsy, such as transjugular and laparoscopic, are performed on patients with bleeding disorders, tumor, obesity, or a solitary kidney. These are done as outpatient procedures, under general anesthesia.
Transjugular biopsy, also called transvenous, involves inserting a small tube through the jugular vein in the neck and guiding it to the kidney using ultrasound. A biopsy needle is passed through the tube to the kidney to obtain a tissue sample. Laparoscopy involves using an endoscope (thin, lighted telescopic instrument) to explore the abdomen. Gas is introduced into the abdomen to separate the organs and to allow the laparoscope to pass. The needle is then inserted through the laparoscope and guided to the kidney with ultrasound.
Percutaneous biopsy generally allows for quicker recovery, causes less pain, and has fewer risks; it is used more frequently.