UNIT EIGHT: ASSISTING WITH CLINICAL LABORATORY PROCEDURES

The Microscope

Magnification System

The magnification system of a microscope consists of:

• Ocular lens (eyepiece) and objective lenses.

• Fine and coarse knobs are used to adjust the clarity of the image.

• Microscopes may be monocular (one eyepiece) or binocular (two eyepieces).

• The ocular lens typically magnifies the image 10 times (10x).

Objective Lenses

In compound microscopes, objective lenses increase the specimen's magnification. These lenses are attached to a revolving nosepiece and typically consist of four different magnifying powers:

1. Scanning Lens:

   • 4x: Shortest objective, used for scanning the field of interest and focusing on an object.

2. Low Power Objective:

   • 10x: Offers greater detail than the scanning lens.

3. High Dry Objective:

   • 40x or 45x: Used for high detail observations.

4. Oil Immersion Objective:

   • 100x: Requires immersion oil to improve resolution and is used for examining extremely small materials like bacteria and platelets.

The total magnification is calculated by multiplying the ocular lens magnification by the objective lens magnification. For instance, if the 10x objective lens is used, the total magnification would be:
$10 imes 10 = 100$

Focusing Mechanism

• Coarse Adjustment: Used only with scanning and low power lenses for quick focusing.

• Fine Adjustment: Used with high-power and oil immersion lenses for precise focusing.

Illumination System

Components of the illumination system include:

• Light source: Located under the stage, providing illumination.

• Condenser: Directs light up through the slide.

• Iris diaphragm: Regulates the amount of light passing through the specimen.

Maintenance of the Microscope

• The microscope should be kept clean, as dirt, oil, and lens secretions can obstruct vision.

• It is advisable to store the microscope in a plastic dust cover when not in use.

• Lenses must be cleaned with lens paper and cleaner; other materials can scratch the lens.

• Proper storage entails placing the low-power objective at the highest position and centering the stage.

• Handling should involve securely supporting the base and holding the arm when moving.

Centrifuge

Functionality

A centrifuge separates solids from liquids by spinning specimens rapidly, using gravitational force to push heavier solids to the bottom and leave lighter liquids on top. Centrifugation is commonly used for separating:

• Blood cells from serum or plasma.

• Solid materials in urine specimens such as cells and crystals.

Centrifuge Types

Centrifuges vary based on their specific use in the laboratory, including:

1. Fixed-Angle Rotor: Specimen cups are held in a rigid position at a fixed angle.

2. Swinging Bucket Rotor: Buckets swing out horizontally during spinning.

3. Microhematocrit Centrifuge: Designed for centrifuging capillary tubes specifically.

Operational Guidelines

• Centrifuge operation is commonly specified in terms of revolutions per minute (rpm).

• Tubes should be balanced evenly for safe operation, ensuring equal size and volume are placed directly across from one another.

• If needed, a tube filled with water can be used as a balance weight. Tubes should be capped to prevent aerosols during operation.

• Never open a centrifuge while in operation.

• Centrifuges should be regularly maintained by cleaning, checking, and lubricating to ensure they operate correctly and safely.

Incubator

Purpose and Function

• Incubators maintain constant temperatures, crucial for microbiological growth. Generally, the temperature settings range from 35° to 37°C (95° to 98.6°F).

• They come equipped with alarm systems to alert if the temperature deviates from the set range.

• Regular checks on temperature and cleaning with a suitable disinfectant are essential practices.

Patient Coaching

Importance of Communication

For many testing procedures, patients require specific instructions:

• Often, the medical assistant reinforces provider instructions, such as fasting for 8 to 12 hours before blood sample collection.

• Clear verbal and written instructions must be provided, including a contact number for queries post-visit.

Legal and Ethical Issues

Laboratories exist primarily to conduct testing due to the prevalence of diseases in human bodies. Ethical considerations include:

• Adherence to safety guidelines to reduce risks.

• Documentation of procedures and patient interactions are essential.

• Communication of results to patients must respect patient privacy as per HIPAA guidelines.

Phlebotomy

Overview

Phlebotomy is essential for diagnosing and monitoring health conditions. The most common method of blood collection is venipuncture, involving:

• A needle puncturing a surface vein, with blood collected into vacuum tubes or syringes.

• Careful procedure execution is vital to prevent health risks.

Bloodborne Pathogens

Healthcare workers face potential exposure to bloodborne viruses including:

• Hepatitis B virus (HBV)

• Hepatitis C virus (HCV)

• Human immunodeficiency virus (HIV)

Training and Certification

Medical assistants may pursue phlebotomy certification via multiple organizations such as:

• American Society of Clinical Pathologists (ASCP)

• American Medical Technologists (AMT)

• National Healthcareer Association (NHA)

Venipuncture Equipment

Proper venipuncture requires specialized equipment commonly stored in:

• Portable trays in hospitals or dedicated phlebotomy chairs in local laboratories.

• If patients have fainting histories, blood collection is safest when performed lying down to mitigate syncope risk.

Summary of Learning Objectives

The clinical laboratory's organization involves personnel responsible for:

• Analyzing blood and body fluids.

• Reporting test results to providers.

• Aiding in patient diagnostics and management.

• Medical assistants may perform CLIA-waived tests.

• Higher-complexity tests must be executed in certified laboratories, adhering to CLIA standards.