Percutaneous Biopsy Techniques

Percutaneous Biopsy: Indications & Prep - Biopsy Blueprint

• Indications (Why?):
  • Malignancy: Diagnosis (primary/mets), staging.
  • Benign lesions: Characterization.
  • Infection/Inflammation: Identify cause (e.g., TB, fungal).
  • Therapy response assessment.
  • Tissue for molecular/genetic analysis.
• Preparation (How?):
  • Informed written consent.
  • Pre-procedure imaging review: Plan safe needle path.
  • Coagulation screen:
    • INR < 1.5
    • Platelet count > 50,000/μL
    • PT/aPTT within normal limits.
  • Medication adjustment: Hold anticoagulants/antiplatelets (e.g., Aspirin 5-7d, Clopidogrel 5-7d, Warfarin 3-5d, NOACs 2-3d).
  • Fasting: 4-6 hours (NPO).
  • Prophylactic antibiotics: For high-risk biopsies (e.g., liver, lung, trans-rectal/colonic).

⭐ For liver biopsy, ensure INR < 1.5 and Platelets > 50,000/μL to minimize bleeding risk.

Percutaneous Biopsy: Guidance Modalities - Imaging Allies

• Ultrasound (USG)
  • Real-time, no radiation, portable.
  • Use: Superficial lesions, soft tissue, fluid.
  • Limits: Operator dependent, gas/bone.
• Computed Tomography (CT)
  • Detail: Excellent anatomical. Use: Deep lesions (chest, abdomen, bone).
  • Radiation: Yes. CT fluoroscopy for near real-time.
• Fluoroscopy
  • Real-time. Use: Bone, GI/GU interventions.
  • Radiation: Yes. Limits: Poor soft tissue contrast.
• Magnetic Resonance Imaging (MRI)
  • Contrast: Superior soft tissue. No radiation.
  • Use: Breast, prostate, MSK.
  • Limits: Costly, long, MR-compatible gear.

⭐ CT is most common for lung biopsies: excellent spatial resolution, visualizes needle path near vital structures.

Percutaneous Biopsy: Needle Selection & Specimen - Needle Know-How

• Needle Categories:
  • Fine Needle Aspiration (FNA):
    • Gauge: 22-27G.
    • Specimen: Cytology.
    • Tips: Chiba (bevel), Franseen/Westcott (cutting) for ↑cellularity.
    • Pros: Safer, less invasive.
  • Core Needle Biopsy (CNB):
    • Gauge: 18-22G.
    • Specimen: Histology (tissue architecture).
    • Types: Tru-Cut (side-notch), automated systems.
    • Pros: ↑Diagnostic yield in solid masses.
• Specimen Handling:
  • FNA: Smears on slides; rinse in medium for cell block.
  • CNB: Formalin for histology; saline for fresh tissue (e.g., lymphoma culture, flow cytometry).

📌 Mnemonic: "Fine for Few cells (FNA), Core for Chunks of tissue (CNB)."

⭐ > The coaxial technique, using an introducer needle, permits multiple core samples through a single pleural/peritoneal puncture, minimizing trauma and risk of tumor seeding along the needle track.

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Percutaneous Biopsy: Technique & Complications - Smooth Ops & Snags

• Guidance: USG (common, real-time), CT (complex cases), Fluoroscopy.
• Needles:
  • FNA (Fine Needle Aspiration): 22-25G (cytology).
  • CNB (Core Needle Biopsy): 14-20G (histology, preferred for architecture).
• Technique: Coaxial approach often preferred (multiple samples, single tract).

• Complications:
  • Common: Pain, minor hematoma, vasovagal reaction.
  • Serious:
    • Hemorrhage (significant): <1-2%.
    • Pneumothorax (lung biopsy): up to 25% (chest tube 5-10%).
    • Infection/Abscess: <1%.
    • Tumor seeding (needle track): Rare.
    • Organ injury (e.g., biliary leak, pancreatitis).
  • 📌 Mnemonic (Major Risks): "BISHOP" - Bleeding, Infection, Seeding, Hematoma/Hemorrhage, Organ injury, Pneumothorax.

⭐ Pneumothorax is the most frequent complication following transthoracic (lung) biopsy; management depends on size and patient symptoms.

High‑Yield Points - ⚡ Biggest Takeaways

• Percutaneous biopsies are vital for diagnosis, staging, and treatment planning.
• Contraindications: uncorrectable coagulopathy (INR > 1.5, platelets < 50,000/μL), no safe access.
• FNA provides cytology; Core Needle Biopsy (CNB) yields histology and tissue architecture.
• Ultrasound (USG) and CT are common imaging guidance modalities.
• Key complications: bleeding, infection, pneumothorax (lung), tumor seeding (rare).
• Coaxial technique reduces needle passes, minimizing trauma and complication risk.
• Pre-procedure: informed consent, review coagulation profile (PT/INR, platelets).