Kidney Biopsy

Each kidney has about one million microscopic size filters, called glomeruli, which normally filter the blood continuously, producing urine to eliminate waste chemicals and water that accumulate from metabolism of foods and drink. Healthy glomeruli do not allow protein or red blood cells from the blood to “leak” into the urine.

While the patient often has no complaints, inflammation (a form of injury) of these filters (thus the term glomerulo -nephritis), results in leakage of protein &/or red blood cells from the bloodstream, through the filters, into the urine. Sometimes there are so many red blood cells in the urine that the urine becomes dark. The amount of protein in the urine can be measured exactly & is a useful guide to the severity of glomerular injury.

Inflammation is often due to some abnormal reaction of the body ‘ s immune system. Severe enough inflammation for a long enough time will result in more & more normal healthy filters being replaced by scar tissue, which does not filter the blood effectively. This results in waste chemicals accumulating in the blood, which is called progressive kidney failure. The end result of this process is kidney failure severe enough to require dialysis or kidney transplantation. However, prompt diagnosis of glomerulonephritis by kidney biopsy allows identification of the nature & severity of glomerular inflammation. Anti-inflammatory drug therapy, if successful, can reverse this process, preventing permanent destruction of glomeruli & restoring kidney health.

Kidney Biopsy Protocol

Your doctor has advised you that based upon your / your child’s complaints, physical examination, urine and blood tests, inflammation (nephritis) of both kidneys is present. Only one kidney need be biopsied, as this condition affects both kidneys equally. A biopsy provides a “tissue diagnosis,” determining the exact nature and severity of this condition, as well as directing potential therapy.

The procedure is typically done during a “one day” hospitalization. The selection of a date depends upon the urgency of the situation and availability of the people, places, and services involved. The most frequent day available for this procedure is Thursday. The Pediatric Nephrology secretary will usually arrange the hospital admission date. Often an additional blood test is done several days before the procedure to be sure that there is no abnormality of the blood clotting system that might increase the risk of bleeding from the biopsy. You are expected at the admitting office at least 2.5 hours before the procedure is scheduled . You / your child must have nothing to eat or drink after midnight because the stomach must be empty before receiving sedative medication. You will be directed to the “one day” (also called ambulatory surgery) unit, and your doctor will meet you there after the nursing staff has spoken with you and measured your height, weight, and blood pressure, etc. Your doctor may apply anesthetic cream to the skin of the back overlying one of the kidneys; the cream is covered with a plastic dressing. It must be applied at least one hour before the biopsy to be effective in numbing the skin.

At the scheduled procedure time, the patient is transferred from the ambulatory surgery unit to the procedure room in the ultrasound area of the Radiology Dept. In the procedure room, ultrasound (sonogram) is used to examine the location, size, and shape of both kidneys. A site is identified on the skin overlying one kidney and the area is cleansed with antiseptic solution and draped with sterile towels. At this time, intra-venous medication is administered by an anesthesiologist, with continuous monitoring of blood oxygen, heartbeat, and blood pressure. Supplemental oxygen is administered via plastic tube under the nostrils. The medication used is very short acting; the child will be asleep within minutes after the infusion is begun, remain asleep during the few minutes it takes to perform the biopsy procedure, and awaken within minutes after it is finished, usually with no memory of the event. Once the patient is asleep, additional anesthetic medication (similar to Novocain used by the dentist) is injected under the skin to numb the tissue between the skin and the kidney. A biopsy needle is inserted into the kidney, and a small fragment of the kidney tissue is removed. There is no incision or stitches. The puncture site is covered with a Band-Aid. Generally, it is less than one hour from the time the child leaves the one day unit to enter the procedure room, until he / she returns.

The only risk to the patient is bleeding, but it is uncommon. Ultrasound imaging is done immediately after the biopsy to see if blood is accumulating around the kidney. If so, this is controlled by pressure over the puncture site for a few minutes until bleeding stops. On occasion, blood can be seen in the urine after the biopsy; if so, the urine will usually clear by the next void or two. The patient is monitored for several hours after the procedure for this potential complication. Fluids are given (by mouth and / or intra-venously) to encourage urine production, bladder filling, and voiding so that the urine can be examined. For any biopsy related discomfort, Tylenol is usually sufficient. The criteria for discharge are voiding clear urine and recovery from sedation; by mid-afternoon, most biopsy patients are discharged home.

Results of the biopsy are usually available within one or two weekdays, and your doctor will arrange to discuss them with you. Should you desire a second opinion about the tissue diagnosis or the treatment plan, the biopsy tissue is mounted on glass slides which can be easily sent elsewhere.

The Pediatric Nephrology staff is available 24 hours a day to answer questions you might have about the kidney biopsy procedure.