How is a pancreatic biopsy performed?

Pancreatic Biopsy Techniques: Approaches and Considerations

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is the preferred method for performing pancreatic biopsies due to its higher safety profile, reduced risk of peritoneal seeding, and additional staging benefits compared to percutaneous approaches. 1

Primary Biopsy Techniques

EUS-Guided Approach (Preferred)

• Procedure: Performed by a gastroenterologist using an endoscopic ultrasound with a fine needle aspiration (FNA) needle (typically 22-27 gauge)
• Advantages:
  • Higher safety profile with minimal risk of complications
  • Lower risk of peritoneal seeding compared to percutaneous approaches
  • Provides additional staging information during the procedure
  • Particularly valuable for small lesions and those in the pancreatic head 1, 2
• Diagnostic yield: 78-84% (may be lower than percutaneous approaches but safer) 3, 4
• When to use: First-line approach, especially for resectable disease and pancreatic head lesions

CT or Ultrasound-Guided Percutaneous Approach

• Procedure: Performed by an interventional radiologist using either CT or ultrasound guidance with an 18-20 gauge needle
• Approaches:
  • Anterior approach (most common, ~79%)
  • Lateral approach (~7%)
  • Posterior approach (~13%) 5
• Diagnostic yield: 90-97% 5, 6
• When to use: When EUS is unavailable or technically not feasible, or for metastatic disease sampling 2

Tissue Acquisition Methods

Fine Needle Aspiration (FNA)

• Provides cytological samples
• Typically requires rapid on-site evaluation (ROSE) for adequacy assessment
• May require more passes (average 2.9) 4

Core Needle Biopsy (CNB)

• Provides histological samples with preserved architecture
• Higher diagnostic yield than FNA (96.7% vs 78.8%) 3
• Requires fewer passes (average 2.4) 4
• Can be performed via both EUS and percutaneous approaches

Clinical Decision Algorithm

1. Determine if biopsy is necessary:

   • Required before neoadjuvant therapy
   • Required for locally advanced/unresectable or metastatic disease
   • Not required before surgical resection for clearly resectable disease 1

2. Select biopsy approach based on:

   • Tumor location (head vs body/tail)
   • Resectability status
   • Institutional expertise
   • Patient factors (coagulopathy, intervening structures)

3. For resectable disease:

   • EUS-FNA is preferred due to lower risk of peritoneal seeding 1
   • If negative, repeat EUS-FNA at least once 1
   • If still negative but high clinical suspicion, proceed with surgery 1

4. For locally advanced/unresectable or metastatic disease:

   • Either EUS-FNA or percutaneous approach is acceptable
   • Biopsy most accessible site for metastatic disease 2
   • Consider laparoscopy with biopsy if repeat FNA is negative 1

Important Considerations and Caveats

• Negative biopsy interpretation: A negative biopsy does not exclude malignancy and should not delay appropriate surgical treatment when clinical suspicion is high 1, 2

• Complication risks:

  • EUS-FNA: Very low risk of complications (minor pain occasionally reported) 3, 4
  • Percutaneous: Slightly higher risk (2-11%) including minor bleeding, pain, inadvertent bowel puncture 5, 6

• Technical success rates: Both EUS and percutaneous approaches have high technical success rates (near 100%) 3

• Repeat biopsy considerations: If initial biopsy is non-diagnostic, repeat EUS-FNA has diagnostic accuracy of 61-84%, particularly valuable for uncinate process lesions or when chronic pancreatitis is present 2

• Special situations: For obstructive jaundice with biliary stricture, EUS-FNA may be less accurate 1

By following these guidelines and selecting the appropriate biopsy technique based on the clinical scenario, the diagnostic accuracy for pancreatic lesions can be optimized while minimizing potential complications.