Kidney biopsy - specialists and information

A kidney biopsy is a medical procedure in which a small tissue sample is taken from the kidney for diagnostic purposes. A kidney biopsy is only carried out if there is reasonable suspicion of serious kidney disease and usually only if other, less invasive diagnostic procedures do not provide clear information. The biopsied tissue is examined microscopically to obtain more detailed information on the type of disease.

Below you will find further information and selected kidney biopsy specialists.

Reasons for a kidney biopsy

The decision as to whether a kidney biopsy is appropriate in a specific case is made by the nephrologist (specialist for kidney diseases). The most common reasons for the diagnostic procedure include

• Haematuria (blood in the urine), if it is accompanied by symptoms of progressive kidney disease (protein in the urine, high blood pressure, low urine output)
• Proteinuria (protein in the urine), if the values are high or other symptoms of kidney disease occur at the same time (water retention in the body tissue, abnormal blood values)
• General signs of acute or chronic kidney failure with an unclear cause (water retention in the tissue, increased creatinine levels, other abnormal blood values, anemia/anemia)
• Abnormal changes in or on the kidney detected by ultrasound or computer tomography, where cancer is suspected
• Problems with the function of a kidney transplant

In the case of blood in the urine, diseases of the kidney and urinary tract are particularly likely @ Tatiana Sidenko /AdobeStock

The so-called protocol biopsy of a transplanted kidney is an exception to the rule that the procedure is only carried out if there is reasonable suspicion of serious kidney disease. It is carried out at many transplant centers on one or more fixed dates after the transplant operation - even if the kidney transplant shows no signs of problems. The protocol biopsy can reveal undetected diseases of the transplant, drug intolerances or rejection processes at an early stage. It is also used to obtain information for research purposes. Protocol biopsy is not uncontroversial among nephrologists.

What are the arguments against a kidney biopsy?

In some cases, a kidney biopsy may not be performed. Absolute contraindications for a kidney biopsy are

• a pathologically increased tendency to bleed due to blood clotting disorders, platelet deficiency (lack of platelets important for clotting) or 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 the case of severe obesity, pregnancy, existing kidney damage or the use of blood-thinning medication. Depending on the case, diagnostic alternatives should be considered.

Procedure for a kidney biopsy

Before the biopsy, blood tests are carried out to rule out infections or blood clotting disorders, as well as an ultrasound examination of the kidney. Blood-thinning medication such as warfarin or heparin should be temporarily discontinued two weeks before the biopsy appointment.

The kidney biopsy is performed under local anesthesia, in exceptional cases also under short anesthesia. The biopsy of an autologous kidney is performed from the back (with the patient lying on their stomach), that of a transplanted kidney from the stomach (lying on their back). The progress of the kidney biopsy is monitored using ultrasound sonography.

After localizing a suitable puncture site, the semi-automatic biopsy gun with the biopsy needle is placed on the disinfected site. In principle, it is not important where exactly the kidney biopsy is taken, as the diseases to be diagnosed manifest themselves anywhere in the kidney tissue. One exception is the diagnosis of tumor-suspicious masses: Here, of course, the exact puncture of the affected area is necessary.

The biopsy needle is carefully advanced up to the connective tissue capsule surrounding the kidney. The patient must now hold their breath for a moment while the doctor triggers the spring mechanism of the biopsy gun. This causes the biopsy needle to shoot into the kidney tissue. This is not painful. The cylindrical tissue sample now contained in the needle is pulled out and placed in a prepared container with a fixative solution. Two samples are often taken in quick succession in order to enable an unequivocal diagnosis. Finally, the entire organ is checked sonographically for bleeding.

The kidney biopsy helps with the precise diagnosis of kidney disease @ anamejia18 /AdobeStock

After the kidney biopsy

A histology laboratory now performs a microscopic examination of the tissue sample.

Following the kidney biopsy, patients spend a day in hospital so that any complications can be dealt with quickly. The patient must remain in bed for 24 hours in a supine position. During this time, a sandbag is placed under the puncture site to compress the puncture channel. The next day, the urine and blood count are checked and the kidneys are examined again by ultrasound.

If there are no signs of complications, patients are discharged home. During the first two weeks after the kidney biopsy, the patient must avoid physical exertion and heavy lifting. If possible, treatment with blood thinners should only be resumed one to two weeks after the biopsy.

Risks of a kidney biopsy

A kidney biopsy is associated with a certain risk of complications:

• There is almost always a more or less obvious hematoma (bruise) in the kidney area and traces of blood in the urine due to the bleeding on the kidney
• Short-term slight anemia after every second procedure
• Temporary pronounced hematuria in three out of one hundred procedures
• Shock symptoms or anemia in about one percent of cases. A blood transfusion is then necessary
• Due to progressive bleeding, a follow-up surgical procedure is required in around one in ten thousand cases
• Blockage of the ureter by a blood clot (rare)

Complications occur 90 percent of the time during the first 12 hours after the procedure. Once patients have left hospital without complications, the residual risk is therefore very low.

Alternatives to kidney biopsy

Gentler biopsy methods are available for patients with an increased risk of complications or only one remaining kidney:

• Conventional biopsy under CT control (CT allows the path of the biopsy needle to be followed even better).
• Laparoscopic biopsy under anesthesia (as part of a laparoscopy, particularly low bleeding)
• Transjugular kidney biopsy (procedure via the jugular vein), also suitable for patients with blood coagulation disorders