Kidney Biopsy

What is a Kidney Biopsy?

A kidney biopsy is a procedure in which a small piece of the kidney is removed with a needle under ultrasound scanning guidance and sent to the pathology lab to be evaluated. It gives us a detailed understanding of what is happening within the kidney.

This information is crucial in helping the Nephrologist understand the following:

• Diagnosis of the kidney condition
• Degree of acute injury vs. chronic damage
• Treatment options
• Prognosis of the kidney condition

When is a Kidney Biopsy required?

A kidney biopsy may be required in specific circumstances when there is a concern for Glomerulonephritis (inflammation in the kidneys) and/or if there is unexplained acute kidney injury.

A biopsy is not performed in the following situations:

• Small shrunken kidneys – which indicates chronic kidney disease
• Single kidney (biopsy can be performed in some cases)
• Anatomical abnormalities (e.g., Polycystic Kidney Disease, horseshoe kidney)
• Hydronephrosis (urine backing up into the kidney)
• Active infection in the kidneys
• Bleeding problem in the patient
• Severe hypertension

How is a Kidney Biopsy Performed?

The following parameters should be met prior to performing a biopsy:

• Good blood pressure control
• Normal coagulation profile
• Patient should not be on blood thinners
• Ultrasound evaluation of the kidneys to rule out structural problems prior to proceeding

The biopsy is usually done with the patient lying on their stomach. The kidneys are visualized with the ultrasound machine. Local anesthesia is given over the side that will be biopsied. A biopsy needle is used to take 2-3 tiny pieces from one kidney. The patient will have to be on strict bed rest for 6-8 hours after the procedure. Urine color will be monitored post-procedure, and occasionally a blood test for blood count and/or a repeat screening ultrasound may be done at a later time to check for bleeding.

Note that in most conditions, the same process affects both kidneys; therefore, only one kidney needs to be biopsied.

Risks of a Kidney Biopsy

The main complications include:

• Pain at the biopsy site – pain if present post-procedure is usually minimal and can be treated with oral paracetamol
• Bleeding – occurs very rarely, with less than 1.6% chance of requiring a blood transfusion and less than 0.5% chance of requiring any kind of procedure to control the bleeding
• Arteriovenous Fistulae – up to a 14% chance, but these usually improve on their own and usually do not cause any symptoms