A kidney biopsy, also known as a renal biopsy, is a procedure where a small sample of kidney tissue is removed for laboratory examination. This is typically performed using a specialized needle inserted through the skin, a method called a percutaneous biopsy. The collected tissue sample allows specialists to examine the cells under a microscope to understand the health of the kidney. The procedure is generally considered safe and is performed with careful preparation and monitoring.
Preparing for the Procedure
Preparation for a kidney biopsy begins with a review of the patient’s medical history. Attention is paid to any history of bleeding disorders or the presence of a single kidney, as these factors influence the approach taken. Blood and urine samples are collected before the procedure to check for active infection or to assess the blood’s ability to clot.
A detailed medication review is also conducted, and patients are instructed to stop taking certain drugs several days before the biopsy. This often includes nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and blood-thinning medications, which increase the risk of bleeding. Some herbal supplements, such as fish oil, may also need to be paused under a doctor’s guidance.
Patients are usually required to fast for a specified period, often around eight hours, before the procedure. This is a standard safety measure for any procedure involving sedation. An intravenous (IV) line is placed in the arm or hand upon arrival, providing a route for fluids or light sedation.
Before the process begins, the care team obtains informed consent, ensuring the patient understands the steps involved and any associated risks. The blood pressure and pulse are measured, and a final check of the coagulation panel confirms the patient’s blood is clotting appropriately for the procedure to proceed safely.
The Biopsy Procedure
The patient is positioned on an examination table, typically lying face down with a pillow placed under the abdomen to stabilize the kidney. Patients with a transplanted kidney are positioned on their back since the organ is located in the lower abdomen.
Imaging guidance, usually an ultrasound, is used to precisely locate the kidney and the target area for the tissue sample. In some instances, a computed tomography (CT) scan may be used instead of ultrasound for guidance.
The skin is thoroughly cleaned with an antiseptic solution and draped to ensure a sterile field. A local anesthetic is injected into the skin and the deeper tissues along the needle’s path to numb the area. A tiny incision may be made at the surface to facilitate the needle’s entry.
The doctor then inserts a specialized biopsy needle through the skin and advances it toward the kidney. The patient may be asked to take a deep breath and hold it for a few seconds as the needle enters the kidney. This temporary breath-holding prevents the kidney from moving with respiration, ensuring the needle remains precisely on target.
The tissue sample is collected using a spring-loaded instrument that quickly advances and retracts the needle, often producing a distinct, audible “click.” The doctor may need to pass the needle two or three times, often through the same entry point, to ensure enough tissue is collected for the lab tests.
A less common alternative is the open biopsy, a surgical procedure performed under general anesthesia. The open method is reserved for patients with certain bleeding risks or anatomical challenges that make the needle biopsy difficult. The needle is withdrawn, and firm pressure is applied to the puncture site to control any immediate bleeding.
Monitoring and Recovery
The patient is moved to a recovery area for close observation. Post-procedure care requires an extended period of bed rest, typically requiring the patient to lie flat for six to eight hours. Staying still helps to minimize the risk of bleeding from the kidney puncture site.
During this recovery period, the healthcare team frequently checks the patient’s vital signs, including blood pressure and heart rate. All urine is collected and inspected for gross hematuria, which is visible blood in the urine. Blood tests are also performed several hours after the procedure to check the patient’s hemoglobin and hematocrit levels.
Mild pain or soreness at the biopsy site is expected and is usually managed with simple pain relievers. Patients are encouraged to drink plenty of fluids to help flush the kidneys and monitor for any persistent blood in the urine. Most patients are discharged later the same day or the following morning once they are stable and show no signs of complication.
Upon returning home, patients are instructed to rest for the remainder of the day and avoid strenuous activities like heavy lifting, jogging, or contact sports for one to two weeks. Patients are also given clear instructions on signs of concerning complications, such as severe pain, fever, or significant, bright red blood in the urine after the first 24 hours.