Kidney Biopsy

Overview

Kidney Biopsy Pre-Procedure Prep

Indications

• Unexplained renal failure
• Nephrotic syndrome
• Isolated non nephrotic proteinuria
• Isolated glomerular hematuria
• Renal masses
• Renal transplant rejection
• Renal transplant dysfunction

Contraindications

• Severe uncontrollable Hypertension
• Uncooperative patient
• Uncorrectable coagulopathy

Pre-Procedure Evaluation

• Hold any blood thinners (See SIR anticoagulation guidelines for specific medications)
• Withhold solid foods except medications (do not hold BP meds) for 6 hours for moderate sedation.
• Informed consent
• Labs: Platelets, PT/PTT, INR, Cr, BUN.
• Choose imaging modality CT vs US (US is the most common and efficient for kidney biopsies)
• Review any prior imaging

Kidney Biopsy Procedure Steps

Positioning

• Native kidneys are most easily biopsied with the patient in a prone position. Both focal and nonfocal biopsies may be performed with the patient in a prone position. Lesions along the lateral edge of the kidney may be difficult to access via an ipsilateral side–down approach.
• A supine position of the patient is chosen for non-focal ultrasound-guided biopsies of a transplanted kidney. Typically, a transplanted kidney is positioned in the right or left lower pelvis and the most direct access is via an anterior approach. A supine anterolateral approach may also be used in obese patients. A supine transhepatic approach is occasionally used to reach anterior renal lesions.

Imaging Guidance

• Ultrasound vs CT depending on body habitus, available equipment, and lesion vs non focal biopsy.

Sedation

• Moderate Sedation most commonly used. General anesthesia if patient cannot hold still.

Procedure

• IV access (18 g preferred)
• Position the patient as appropriate and localize the lower pole of the kidney by imaging
• Lower pole of the native kidney has the lowest risk of puncturing a vessel and causing a perinephric hematoma
• Determine kidney size and detect unexpected anatomical barriers like cysts that would indicate the use of the contralateral kidney
• Make a skin mark to identify where the biopsy will be indicated for the lower pole target
• Prep the site of the skin mark and anesthetize the subcutaneous tissues using 1% local Lidocaine
• Under imaging guidance, carefully place the tip of the 17 g coaxial needle into the lower pole cortex and verify positioning by imaging. Once in position, pass the 18 g biopsy needle through the coaxial needle to obtain samples.
• 3-4 core biopsy samples are recommended. Goal is to obtain renal cortex (or lesion) tissue, avoiding the central kidney.
• Follow up imaging with US or CT to confirm no immediate bleeding. If a small hematoma develops, watch for 15-20 minutes for growth. Keep Systolic BP <145 mmHg.

Kidney Biopsy Post-Procedure

Post-Operative Care

• Pressure over biopsy site for 1 hour. Patient can lay the flank over a rolled up towel.
• Close observation of vital signs and symptoms of hematoma for 3-6 hours is absolutely necessary.
• Vital signs should be monitored every 15 minutes for 2 hours, every 30 min for 2 hours, then every hour for 2 hours post procedure.
• If there is worsening pain over the flank, re-image with CT or ultrasound and check CBC.
• If bleeding rapidly, blood transfusion and transcatheter embolization may be necessary.

Potential Complications

• Perinephric and subcapsular hematoma
• Retroperitoneal hematoma
• Hematuria
• Arteriovenous fistula or Renal Artery pseudoaneurysm