- What is kidney (renal) biopsy?
Renal biopsy is a bedside procedure in which a small piece of tissue is removed from the kidney (using a thin long cutting needle) and submitted for study under the microscope by a pathologist (a doctor who diagnoses diseases from the study of samples of tissues and body fluids).
- Why is kidney biopsy done?
Renal biopsy is done to diagnose the cause of unexplained urinary abnormalities (protein leak or red blood cells in urine) or unexplained kidney failure and to assess the reversibility of kidney disease. It is also done to categorize certain diseases to guide treatment.
- Is kidney biopsy done to diagnose cancer?
There is a misconception among public that biopsy is done mainly to diagnose cancer. In patients having kidney disease, biopsy is done for a different reason: to diagnose the disease that has affected the filters in the kidney (nephrons), to assess the stage of involvement and to decide whether the disease course will be modified by specific treatment.
- Is kidney biopsy done for both the kidneys?
Samples from one kidney are sufficient to diagnose the cause for the patient’s kidney problems. Biopsy will be done preferably on the left side as it is easier to approach; if biopsy cannot be done on the left kidney, it will be done on the right side.
- What are the precautions taken by the doctor before kidney biopsy?
The most common post-biopsy complication is passing blood in the urine (hematuria). To minimize this complication,
a) Tests are done to make sure that the patient has normal clotting status.
b) The doctor checks the patient’s medication list and advises to stop medications (other than Aspirin) that interfere with clotting process; such medications are stopped 5 days prior to the procedure; depending on the need for these medications, the doctor starts the patient on alternative short-acting anticlotting medications.
c) Blood pressure is brought under control before a kidney biopsy is performed in patients having uncontrolled hypertension.
d) Two or three sessions of hemodialysis are done before a kidney biopsy if the patient is having advanced kidney failure.
- Is kidney biopsy done as outpatient procedure?
No, the patient requires admission for the procedure at around 7.30 am on the day fixed for kidney biopsy (if not admitted earlier for management of uncontrolled hypertension or advanced kidney failure). There is no specific instruction for that day morning: the patient can have the bath, breakfast (preferably light) and scheduled medications as before. A small cannula will be inserted into a vein of the hand soon after admission.
- How is the procedure done?
Kidney biopsy is done under ultrasonogram guidance for better localization of the biopsy site and to minimize the risk of complications.
The patient lies on abdomen for a few minutes (that is why light breakfast is advised for that day morning).
Using ultrasonogram, the site of biopsy needle entry is decided. The area of biopsy in the back is cleaned with antiseptic solution. Medication is injected at that point to provide local anesthesia and pain relief.
An incision is made with a sterile surgical blade once the injected area is numb. The biopsy needle is introduced through the site and guided to the kidney using ultrasonogram. Patient is instructed to hold breath once the kidney surface is reached; the trigger on the biopsy needle is released then to cut the tissue.
The needle is then taken out and the biopsy sample is collected under Saline solution. The process will be repeated two to three times for collection of at least two good pieces. The wound will be covered with sterile gauze and plaster after the procedure is completed. The entire procedure takes 10 minutes’ time.
- Will there be variations from the procedure mentioned above?
There will be variations from the above mentioned procedure in a) renal transplant recipients – they lie on their back during biopsy, b) children – renal biopsy will be done under sedation for better cooperation; hence they will be advised not to take food in the morning and will be started on intravenous fluids from that day morning, c) (very rarely) patients who undergo surgical procedures in the kidney region for some other purpose and also require kidney biopsy for a different reason – renal biopsy will be done in Operating Room under anesthesia if he is otherwise stable after completion of the main procedure and d) pregnant women – if kidney biopsy is absolutely necessary, it is usually done in a sitting posture.
- Are there any complications of kidney biopsy?
Temporary drop in blood pressure can occur in certain patients during the procedure. Bleeding into the urinary tract as evidenced by hematuria can occur in about 5% of patients undergoing renal biopsy. Most often this bleeding will be minor and transient and it subsides on its own. Rarely massive bleeding associated with severe pain can occur around the biopsy site; this complication may require transfusion of blood and very rarely, surgical intervention if bleeding is persistent. Injury to neighboring organs is extremely rare when biopsy is done under ultrasound guidance.
- Can the kidney be damaged by kidney biopsy?
Kidney biopsy is performed on a diseased kidney; worsening in kidney function following kidney biopsy is almost always related to the kidney disease per se. Kidney damage secondary to renal biopsy is extremely rare as only a few nephrons are removed for biopsy. A very large post biopsy blood collection around the biopsied kidney (hematoma) is the only instance in which kidney biopsy can compromise the kidney function on its own; the occurrence of this complication is extremely rare. Overall the benefits of renal biopsy are much more than the risks in the context it is planned.
- What are the precautions taken following the biopsy?
The patient will be under bed rest and observation in the hospital overnight. Blood pressure and pulse rate will be periodically monitored. A sample of urine passed each time should be kept in small containers for comparison and assessment of bleeding.
- When is the patient discharged after biopsy?
The patient will be discharged at 4pm the next day if there are no problems in the post biopsy period. If there is moderate to severe bleeding following biopsy, ultrasound screening may be necessary to look for hematoma around the kidney and discharge will be postponed until there is no ongoing bleeding.
- When can the usual activities be resumed?
The patient can resume normal activities two days after the biopsy if there is no hematuria.
- Will there be a need for repeat biopsy?
Repeat biopsy may be needed a) within a few days if adequate tissue was not obtained during the first procedure or b) several months or years later if the clinical condition at that point of time warrants it.
- When will the biopsy report be ready?
The report will be ready in 4 to 5 days’ time.