Specimen Collection and Processing

Specimen Collection and Processing

Specimen Collection and Processing

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Types of Cytology Specimens - Tiny Tells All

Cytopathology involves diagnosing diseases by examining individual cells or small cell clusters.

  • Advantages: Rapid diagnosis, minimally invasive procedures, cost-effective.
  • Limitations: Risk of sampling error, loss of tissue architecture details.

Specimen Categories:

FeatureExfoliative CytologyAspiration Cytology (FNA)
DefinitionStudy of cells shed spontaneously or mechanically.Study of cells obtained by needle aspiration.
Subtypes- Spontaneous (e.g., urine, sputum, effusions)
- Mechanical (e.g., Pap smear, brushings)
Fine Needle Aspiration (FNA)
Common SitesCervix, bronchi, bladder, body cavities.Thyroid, lymph nodes, breast, liver, lung.

⭐ Cytology offers a rapid, minimally invasive, and cost-effective diagnostic approach, especially for cancer screening and diagnosis.

Exfoliative Cytology Collection - Surface Sleuthing

Exfoliative cytology involves collecting cells shed naturally or dislodged from surfaces. Key methods include:

SiteCollection Method(s)Common Fixative(s)
GynaecologicalPap smear (Conventional, LBC)95% Ethanol, LBC-specific preservatives
RespiratorySputum, Bronchial washings/brushings, BALSaccomanno fixative (sputum), 95% Ethanol/Cytolyt
Urinary TractVoided urine (mid-stream, >30-50mL), CatheterizedFresh (ideal), 50% Ethanol, Saccomanno
GITBrushings (endoscopic)95% Ethanol
Body FluidsPleural, Peritoneal, CSF (aspirates)Fresh, Heparin (if bloody), 50% Ethanol

⭐ Liquid-Based Cytology (LBC) for Pap smears significantly reduces obscuring elements like blood and mucus, improving sensitivity.

📌 Pap Smear Adequacy (Bethesda): Satisfactory? Cells (squamous >5000 LBC, 8000-12000 conv.), Endocervical/TZ component present, No obscuring factors (No Obscuring Blood, Inflammation, Mucus >75%).

FNAC: Procedure & Evaluation - Needle Ninjas

Fine Needle Aspiration Cytology (FNAC) is a key diagnostic tool.

  • Indications: Palpable lesions (thyroid, breast, lymph nodes); deep lesions (USG/CT guided: liver, lung).
  • Contraindications: Bleeding disorders, uncooperative patient.
  • Technique:
    • Needle: 22-27 gauge.
    • Aspiration (syringe) or non-aspiration/capillary (Zajdela technique).
    • Imaging guidance (USG/CT) for deep sites.
  • ROSE (Rapid On-Site Evaluation): Assesses sample adequacy, ↑diagnostic yield.

    ⭐ Rapid On-Site Evaluation (ROSE) during FNAC dramatically increases sample adequacy and diagnostic yield, reducing the need for repeat procedures.

  • Common Sites: Thyroid, lymph nodes, breast, salivary glands, liver, lung.
  • Complications (Rare): Hematoma, pneumothorax (lung), infection.

Cytology Processing: Smears & Stains - Slide Stories

  • Smear Techniques: Direct spread/pull-apart, crush (cellular samples), cytospin (fluid samples).
  • Fixation:
    • Wet Fix (e.g., 95% ethanol, methanol): For Pap stain; preserves nuclear detail.
    • Air Drying: For MGG stain; preserves cytoplasmic/matrix features.
  • Stains:
    • Papanicolaou (Pap): Polychromatic. Excellent nuclear detail. 📌 HOG EAts (Hematoxylin, OG-6, EA-50).
    • May-Grünwald Giemsa (MGG): Romanowsky. Good cytoplasmic & matrix detail.
  • Cell Block: From sediment/fragments. For architecture, H&E, IHC, molecular studies.
FeaturePapanicolaou (Pap) StainMay-Grünwald Giemsa (MGG) Stain
FixationWet (95% ethanol)Air drying
Nuclear Detail+++ (Excellent, crisp)++ (Good)
CytoplasmTransparent, differentiationOpaque, granules
Primary UseCancer screening, nuclear morphologyHematology, cytoplasmic detail

⭐ The Papanicolaou (Pap) stain is a polychromatic stain ideal for assessing nuclear details and cytoplasmic differentiation, crucial for cancer diagnosis.

High‑Yield Points - ⚡ Biggest Takeaways

  • FNAC: Rapid diagnosis with 22-25G needles; thinner for vascular, thicker for fibrotic.
  • Fixation: 95% Ethanol for Pap (nuclear detail); air-dry for Romanowsky (cytoplasmic).
  • Stains: Papanicolaou for nuclear; Romanowsky (Giemsa, MGG) for cytoplasmic/matrix.
  • LBC: Cleaner smears, ↓ artifacts, allows ancillary tests (e.g., HPV DNA).
  • Cell blocks: From FNAC/fluids, crucial for IHC and architecture.
  • Adequacy: Essential (e.g., Bethesda thyroid: ≥6 groups, ≥10 cells each).

Practice Questions: Specimen Collection and Processing

Test your understanding with these related questions

Which of the following screening methods is NOT effective for early detection of cancer in asymptomatic women?

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Flashcards: Specimen Collection and Processing

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A Thy2 FNAC result defines the thyroid lesion as _____

TAP TO REVEAL ANSWER

A Thy2 FNAC result defines the thyroid lesion as _____

non-neoplastic

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