A kidney biopsy is a procedure in which a doctor removes a small piece of kidney tissue for laboratory analysis to:

• diagnose a suspected kidney disease, 
• determine the severity of kidney damage, and
• monitor kidney malfunction and/or deterioration. 

The biopsy is usually performed by inserting a thin needle through the skin, guided by an imaging device. This method, called percutaneous kidney biopsy (PKB), is considered a safe procedure. All medical procedures carry risks, however, and bleeding is the most common risk and complication of PKB, particularly for patients who take anticoagulants or similar medications for heart conditions.

Physicians at Kidney Health Australia have proposed a set of guidelines for pre-biopsy medication management in an Asian Pacific Society Of Nephrology review that focuses on renal biopsy recommendations.*

What are the risk factors for PKB?

Patients at highest risk for bleeding include those with a history of:

• a coronary stent,
• symptomatic myocardial ischemia,
• peripheral vascular disease, and
• previous ischemic stroke.

Other patients at high risk are those who are also at risk for thromboembolism, including those with:

• a mechanical mitral valve,
• a mechanical aortic valve, and 
• additional stroke risk factors.

Guidelines prior to biopsy

For those who are at high risk of a cardiovascular event:

• Continue to take aspirin, including patients who have a history of coronary stent, symptomatic myocardial ischaemia, peripheral vascular disease, and previous ischaemic stroke.

For those who are at high risk for thromboembolism (blood clot):

• Start bridging anticoagulation medication (taking a short-acting blood thinner 10 to 12 days before a surgery or procedure for when normal warfarin medication must be paused). This includes “patients with a mechanical mitral valve, a mechanical aortic valve and additional stroke risk factors.”

For those who are at low risk for a cardiovascular event, the following guidelines are recommended.

• Stop taking aspirin three to seven days before to renal biopsy. This helps prevent both minor and major bleeding.

All patients are recommended to stop taking the following medications prior to biopsy:

• Five to seven days: adenosine diphosphate (ADP) inhibitors (clopidogrel, prasugrel, ticagrelor)
• Five days: warfarin
• 48 to 72 hours: direct thrombin inhibitors (dabigatran) and factor Xa inhibitors (rivaroxaban, apixaban)
• 24 hours: low molecular weight heparin
• Four to six hours: unfractionated heparin

With this information in mind, the guidelines also suggest that before the biopsy, “platelet count should be above 50 000/μL, and the INR should be less than 1.5.”

Post-biopsy recommendations

Doctors recommend that antiplatelet and anticoagulant medications not be restarted until 24 to 48 hours after a successful biopsy. This is the window of time in which complications, if they arise, will occur. For patients at high risk for cardiovascular events, continuation of aspirin therapy is recommended.

For the full review article, entitled “KHA‐CARI Guideline recommendations for renal biopsy,” please visit the Wiley Online Library.

*MacGinley, R., Champion De Crespigny, P. J., Gutman, T., Lopez-Vargas, P., et. al. (2019, Sept. 6). “KHA‐CARI Guideline recommendations for renal biopsy.” Asian Pacific Society Of Nephrology.