Percutaneous Biopsy Techniques

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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.

Percutaneous kidney biopsy with ultrasound and CT

⭐ 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.

FNA and core biopsy needle tip designsoka

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).

Practice Questions: Percutaneous Biopsy Techniques

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Flashcards: Percutaneous Biopsy Techniques

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A carotid cavernous fistula requires a definitive treatment, which currently involves the _____ technique using a balloon or coil

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A carotid cavernous fistula requires a definitive treatment, which currently involves the _____ technique using a balloon or coil

endovascular

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