What are the guidelines for performing a renal biopsy in patients with impaired renal function?

From the Guidelines

Renal biopsy in patients with impaired renal function should be performed when the diagnostic information will likely alter management and the benefits outweigh the increased bleeding risk associated with uremia. The decision to perform a renal biopsy in these patients requires careful consideration of the risks and benefits, with several key guidelines to follow.

Key Considerations

• Prior to biopsy, patients should have coagulation studies (PT/INR, PTT, and platelet count) with correction of any abnormalities; platelets should ideally be above 50,000/μL and INR less than 1.5 1.
• Blood pressure should be well-controlled (typically below 160/90 mmHg) to reduce bleeding risk.
• Medications that affect coagulation, including antiplatelet agents, NSAIDs, and anticoagulants, should be discontinued when possible.
• For patients with severe renal impairment (eGFR <30 ml/min), consider administering desmopressin (DDAVP) 0.3 μg/kg IV 30 minutes before the procedure to improve platelet function.
• Real-time ultrasound guidance is essential for all renal biopsies in this population to minimize complications.
• Post-procedure, patients require close monitoring for at least 6-8 hours with frequent vital sign checks and observation for gross hematuria or flank pain.

Patient Selection

The presence of monoclonal gammopathy in patients with renal manifestations deserves a thorough evaluation, especially in those under 50 years old 1. Older age (≥70 years) should not discourage biopsy as most MGRS-related renal diseases occur in patients over 50 years. In young and physically fit patients who are eligible for kidney transplantation, a kidney biopsy should be performed provided the kidneys are not markedly shrunken.

Procedure

Transjugular kidney biopsy is an option in high-risk patients from whom it would otherwise be difficult to obtain kidney tissue 1. The renal biopsy, though a relatively safe medical procedure, should be undertaken only after serious consideration of possible morbidity and rare mortality that can occur with this invasive technique 1.

Diagnostic Evaluation

The correct diagnosis requires a well-trained renal pathologist with thorough knowledge of not only renal pathology but also renal medicine to correlate intricate tissue-derived information with detailed and sometimes subtle clinical data 1. The sample of renal tissue needs to be examined with optimal methods to allow for a complete evaluation, including light microscopy (LM), immunohistochemistry (IHC), and electron microscopy (EM) 1.

From the Research

Guidelines for Performing a Renal Biopsy

The guidelines for performing a renal biopsy in patients with impaired renal function are as follows:

• The decision to perform a renal biopsy should be based on the potential benefit of obtaining renal histology outweighing the risks of the procedure 2.
• Percutaneous renal biopsy is a relatively safe procedure with life-threatening complications occurring in less than 0.1% of biopsies 2.
• The use of ultrasonography and automated-gun biopsy devices has improved the technique of renal biopsy 2.
• Patients with impaired renal function, such as those with advanced renal insufficiency, are at higher risk of bleeding complications 2, 3.
• The use of the PFA-100 may replace the bleeding time and is now considered as a more valuable screening test for prebiopsy identification and management of patients with impaired haemostasis 2.

Contraindications and Alternative Methods

• Historical contraindications for percutaneous renal biopsy, such as bleeding diathesis, morbid obesity, and solitary kidney, have been called into question in the literature 4.
• Alternative methods for kidney biopsy, such as transjugular kidney biopsy or surgical biopsy, may be indicated in limited circumstances 2, 4.
• A laparoscopic approach or a radiology interventional procedure through the internal jugular vein may be considered for obtaining a kidney tissue sample if there is an urgent indication and a bleeding tendency cannot be adequately corrected 5.

Safety and Complications

• Percutaneous renal biopsy is safe and effective in the majority of kidney units for the evaluation of medical renal disease 4.
• Rates of bleeding range from 0.3%-7.4%, and nephrectomy rates are exceedingly low (0.1%-0.5%) 4.
• Major bleeding after a percutaneous renal biopsy can usually be managed with selective arterial embolization of the injured renal vessel 5.
• Overweight patients, as well as those with higher creatinine, lower hemoglobin, higher blood pressure, and biopsy due to AKI, had higher chances to develop complications 3.

Patient Selection and Preparation

• Patients should be selected according to standardized criteria, and biopsy should be performed using a modern technique (automated biopsy needles under ultrasound guidance) 6.
• Correction of anaemia and blood pressure is to be considered before the biopsy 3.
• A coagulation disorder needs to be excluded beforehand, and an elevated blood pressure must be reduced to the normotensive range with medications 5.