Kidney Biopsy - Specialists and Information

The nephrologist (a specialist in kidney diseases) determines whether a kidney biopsy is appropriate in a specific case.

The most common reasons for this diagnostic procedure include:

• Hematuria (blood in the urine), provided it is accompanied by symptoms of progressive kidney disease (protein in the urine
• high blood pressure, low urine output)
• Protein in the urine, provided the levels are high or other symptoms of kidney disease are present (fluid retention in body tissues, abnormal blood test results)
• General signs of acute or chronic kidney failure of unknown cause (fluid retention in tissues, elevated creatinine levels, other abnormal blood test results, anemia)
• Abnormal changes in or around the kidney detected by ultrasound or CT scan, where cancer is suspected
• Problems with a kidney transplant

Blood in the urine is primarily associated with diseases of the kidneys and urinary tract @ Tatiana Sidenko /AdobeStock

The procedure is also performed as part of a routine biopsy of a transplanted kidney, even in the absence of a reasonable suspicion of severe kidney disease.

In most transplant centers, it is performed on one or more scheduled dates following the transplant surgery—even if the kidney transplant shows no signs of problems.

A protocol biopsy can detect the following conditions:

• Undetected diseases of the transplant 
• Drug intolerances or
• Early-stage rejection processes

It also serves to gather information for research purposes. The protocol biopsy is a subject of debate among nephrologists.

In some cases, a kidney biopsy must not be performed.

Absolute contraindications for a kidney biopsy include:

• Pathologically increased tendency to bleed due to blood clotting disorders
• Thrombocytopenia (low platelet count, which are essential for clotting)
• Diseases of the blood vessel walls
• Uncontrolled severe high blood pressure
• Urinary tract infections
• Presence of only one kidney

The risk of complications from a kidney biopsy increases in cases of severe obesity, pregnancy, existing kidney damage, or when taking blood-thinning medications. Depending on the case, alternative diagnostic options should be considered.

Before the biopsy, an ultrasound and blood tests are performed to rule out infections or blood clotting disorders.

You should temporarily stop taking blood-thinning medications such as warfarin or heparin two weeks before the biopsy appointment.

A kidney biopsy requires local anesthesia; in exceptional cases, general anesthesia may be used.

A biopsy of the patient’s own kidney is performed from the back. The patient lies on their stomach during the procedure. 

For a transplanted kidney, the biopsy is performed from the front. The patient lies on their back. Doctors monitor the progress of the kidney biopsy using ultrasound. 

The doctor first disinfects the puncture site and positions the semi-automatic biopsy gun with the biopsy needle there. 

The exact location of the kidney biopsy is not critical, as the conditions being diagnosed can occur anywhere in the kidney tissue. An exception is the diagnosis of suspected tumors: In this case, precise puncture of the affected area is necessary.

The doctor then carefully advances the biopsy needle until it reaches the surrounding connective tissue capsule. The patient must now hold their breath for a moment while the doctor activates the spring mechanism of the biopsy gun. 

This causes the biopsy needle to shoot into the kidney tissue. This procedure is not painful. The doctor removes the cylindrical tissue sample contained within the needle and places it in a container with a fixative solution. 

The doctor often takes two samples in quick succession to ensure an unambiguous diagnosis. Finally, an ultrasound examination of the entire organ is performed to check for bleeding.

A kidney biopsy helps in the accurate diagnosis of kidney disease @ anamejia18 /AdobeStock

A histology lab then performs a microscopic examination of the tissue sample.

Following the kidney biopsy, patients spend one day as inpatients in the hospital. This allows hospital staff to respond quickly to any complications. 

After the procedure, the patient must remain in bed for 24 hours, lying on their back. A sandbag is placed on the puncture site during this time to apply pressure to the puncture site. The next day, urine and blood tests are performed, along with another ultrasound examination of the kidney.

If there are no signs of complications, the patient may go home. During the first two weeks after the kidney biopsy, the patient must avoid physical exertion and heavy lifting. If possible, the patient should wait one to two weeks after the biopsy before resuming treatment with blood thinners.

A kidney biopsy carries a certain risk of complications:

• A hematoma (bruise) of varying severity almost always forms in the kidney area
• Traces of blood may appear in the urine
• Mild, short-term anemia occurs in one out of every two procedures
• Temporary, pronounced hematuria in three out of every hundred procedures
• Symptoms of shock or anemia in about one percent of cases. A blood transfusion is then necessary
• Due to ongoing bleeding, a follow-up surgical procedure is required in about one in ten thousand cases
• Blockage of the ureter by a blood clot (rare)

Complications occur in 90 percent of cases within the first 12 hours after the procedure. If patients have been discharged from the hospital without complications, the residual risk is therefore very small.

For patients at increased risk of complications or those with only one remaining kidney, minimally invasive biopsy methods are available:

• Conventional biopsy under CT guidance (CT allows for even better tracking of the biopsy needle’s path.)
• Laparoscopic biopsy under general anesthesia (performed as part of a laparoscopy, with minimal bleeding)
• Transjugular kidney biopsy (procedure via the jugular vein), also suitable for patients with blood clotting disorders