[U5] Specialized Areas of Medical Technology

Hematology

Specialized Area of Medical Technology

Study of blood cells and coagulation

• Encompasses analyses of the concentration, structure, and function of cells in blood;

• Their precursors in the bone marrow

• The chemical constituents of plasma or serum intimately linked with blood cell structure and function

• The function of platelets and proteins involved in blood coagulation

What are the areas tackled in Hematology?

Complete Blood Count (CBC)

Hematology Procedure

Series of whole-blood tests to determine the quantity and other characteristics of blood cells

RBC Count

RBC Parameters

Expressed as the number of red blood cells per cubic mL

Hemoglobin

RBC Parameters

Primary constituent of RBC cytoplasm and transports molecular oxygen from the lungs to tissues

Hematocrit

RBC Parameters

Ratio of the volume of packed RBC to the volume of whole blood

Mean Cell Volume (MCV)

RBC Parameters

Reflects RBC diamater (fL)

Mean Cell Hemoglobin (MCH)

RBC Parameters

Expresses the mass of hemoglobin per cell (pg)

Mean Cell Hemoglobin Concentration (MCHC)

RBC Parameters

Reflects RBC staining intensity and amount of central pallor (g/dL)

RBC Distribution Width (RDW)

RBC Parameters

Expresses the degree of variation in RBC volume

Anisocytosis

RBC Parameters

Variation in the RBC size

WBC Count

WBC Parameters

The number of WBCs in 1mm³ of blood

Leukopenia

WBC Parameters

Decreased WBC count

Leukocytosis

WBC Parameters

Increased WBC count

Differential Count

WBC Parameters

Review, classification, and tabulation of usually 100 white blood cells in a stained peripheral blood film

Neutrophils

WBCs

Granulocyte; Phagocytic cells with multilobed nuclei

Cytoplasm has pink or lavender-staining granules filled with bactericidal substance

Neutrophilia

WBCs

Increased neutrophil count

Neutropenia

WBCs

Decreased neutrophil count

Band Neutrophil

WBCs

Slightly less mature than neutrophils, with a non-segmented nucleus in a U or S shape

Eosinophils

WBCs

Granulocyte; Cells with round, bright orange-red cytoplasmic granules filled with proteins involved in immune regulation

Eosinophilia

WBCs

Increased eosinophil count

Basophils

WBCs

Granulocytes; Cells with dark purple, irregular cytoplasmic granules that obscure the nucleus, granules contain histamine

Basophilia

WBCs

Increased basophil count

Lymphocytes

WBCs

Agranulocytes; Nearly round, larger than RBC, dark-staining found featureless nuclei and has thin rim of nongranular cytoplasm

Provides host immunity

Lymphocytosis

WBCs

Increased lymophocyte count

Lymphocytopenia

WBCs

Decreased lymphocyte count

Monocytes

WBCs

Agranulocyte; Immature marcophage; slightly larger diameter than other WBCs, blue-gray cytoplasm with fine azure granules, nucleus is usually indented or folded

Monocytosis

WBCs

Increased monocyte count

Platelet Count

Platelets Parameters

Number of platelets per cubic mm

Mean Platelet Volume (MPV)

Platelets Parameters

Average size of platelets

Coagulation Test

Hematology Procedure

Test for clotting factors

Prothrombin Time (PT)

Coagulation Test

Measures the time it takes for blood to clot after adding tissue factor (thromboplastin)

Activated Partial Thromboplastin Time (aPTT)

Coagulation Test

Measures the time it takes for blood to clot after adding a contact activator and phospholipids to shorten clotting time

Thrombin Time (TT)

Coagulation Test

Measures the time it takes for blood to clot after adding thrombin, measures the final step of clotting cascade

Fibrinogen Assay

Coagulation Test

Measures the amount (or activity) of fibrinogen protein in blood

D-Dimer Assay

Coagulation Test

Detects D-dimer fragments, which are produced when fibrin clots are broken down (degraded fibrin)

Plasma

Blood Component

Liquid portion of unclotted blood, contains clotting factors such as fibrinogen

Serum

Blood Component

Liquid portion of clotted blood, has no clotting factors (consumed during clotting)

Erythrocytes

Blood Component

Term for red blood cells

Leukocytes

Blood Component

Term for white blood cells

Thrombocytes

Blood Component

Term for platelet

First responders to infection, primarily bacterial and fungal

What is the primary function of Neutrophils?

Defense against parasitic infections and modulations of allergic and inflammatory responses

What is the primary function of Eosinophils?

Release histamine and other chemicals to mediate allergic and inflammatory responses

What is the primary function of Basophils?

Migration into tissues to become macrophages (“garbage trucks” of the immune system)

What is the primary function of Monocytes?

Core cells of the adaptive immune system, including T cells (target and kill viruses and tumors) and B cells (produce antibodies)

What is the primary function of Lymphocytes?

Microbiology

Specialized Area of Medical Technology

Focuses on the detection, characterization, and quantification of pathogens from patient samples to enable diagnosis, treatment, and management of infections

Bacteriology

Specialized Area of Medical Technology

Study of bacteria

Mycology

Specialized Area of Medical Technology

Study of fungi

Virology

Specialized Area of Medical Technology

Study of viruses

Parasitology

Specialized Area of Medical Technology

Study of parasites

Bacteria

Microbiology

Single-celled prokaryotic (no true nucleus) organisms that can reproduce independently

Fungi

Microbiology

Eukaryotic organisms with cell walls that contain chitin

Virus

Microbiology

Acellular, obligate intracellular parasites (need invade host cell to reproduce), consist of DNA or RNA encased in a protein coat

Parasites

Eukaryotic organisms that live in or on a host, deriving nutrients from host at the host’s expense.

Gram Stain

Microbiology Procedure

Differential staining technique that divides bacteria into gram-positive and gram-negative based on their cell wall structure

Rapidly provides information that is used by the clinician for selecting appropriate antimicrobial therapy

Primary Stain - Gram Stain

Gram Stain

First step, stains all bacterial cells purple

Cystal Violet

Gram Stain

Reagent used in the primary stain

Mordant - Gram Stain

Gram Stain

Second step, reagent complexes with crystal violet to form large insoluble complexes (crystal violet-iodine (cv-i) complexes) inside the cell

Gram Iodine

Gram Stain

Reagent used in the mordant

Decolorization - Gram Stain

Gram Stain

Third step, critical differential step where dye complex from Gram-negative bacteria is washed out

Acetone or Alcohol

Gram Stain

Reagent used in decolorization

Counterstain - Gram Stain

Gram Stain

Fourth and last step, staining of colorless gram-negative cells with pink/red dye

Safranin

Gram Stain

Reagent used in counterstain

Gram-Positive Bacteria

Gram Stain

Bacteria with a thick layer of peptidoglycan (up to 90% of the cell wall) that cen retain purple CV-I complex inside the cell

Gram-negative Bacteria

Gram Stain

Bacteria with a relatively thin layer of peptidoglycan and an outer membrane high in lipids that are unable to retain purple CV-I complex, and instead retains pink safranin counterstain

Acid-Fast Stain

Microbiology Procedure

Differential staining technique used to identify bacteria with a waxy cell wall (containing large amounts of mycolic acid, therefore high resistance to decolorization by gram-stain/acid-alcohol)

Ziehl-Neelsen Method Acid-Fast Stain

Acid-Fast Stain

Mordant used is heat (and phenol), which physically melts away waxy mycolic acid

Kinyoun Method Acid-Fast Stain

Acid-Fast Stain

Mordant used is high concentration of phenol to achieve dye penetration without heat.

Primary Stain - Acid-Fast Stain

Acid-Fast Stain

First Step, flooding of smear with pink dye reagent to drive stain into waxy cell wall in addition to mordent, where all cells become pink

Decolorization - Acid-Fast Stain

Acid-Fast Stain

Second step, flooding of smear until dye runs clear, where acid-fast cells remain pink while non-acid-fast cells become colorless

Counterstain - Acid-Fast Stain

Third and last step, flood smear with reagent to counterstain non-acid-fast cells blue

Carbolfuchsin

Acid-Fast Stain

Reagent used in primary stain

Acid-Alcohol

Acid-Fast Stain

Reagent used in decolorization

Methylene Blue or Malachite Green

Acid-Fast Stain

Reagent used in counterstain

Poikilocytosis

RBC Parameters

Presence of abnormally shaped RBCs

Direct Sputum Smear Microscopy (DSSM)

Microbiology Procedure

Fundamental to the detection of infectious cases e.g. pulmonary tuberculosis (TB), recommended for case finding among adults and children who can expectorate (cough up and spit out material from respiratory tract) (NTP)

10% Potassium Hydroxide (KOH)

Microbiology Procedure

Direct microscopic detection of fungal elements in clinical specimens

Clears the specimen of proteinaceous and keratinous substance (skin scrapings and nail clippings)

Nonselective Media

Types of Culture Media

Media that supports the growth of most nonfastidious microbes (grow easily without special or complex nutrients/conditions)

Example: Blood Agar

Selective Media

Types of Culture Media

Media that supports the growth of one type or group of microbes but not another

Example: MacConkey Agar for gram-negative bacilli, Columbia agar with colistin and nalidixic acid (CNA) for gram-positive microbes

Differential Media

Types of Culture Media

Allows grouping of microbes based on different characteristics demonstrated on the medium

Enriched Media

Types of Culture Media

Contains growth enhancers that are added to nonselective agar to allow fastidious organisms to flourish

Example: Chocolate Agar

Enrichment Broth

Types of Culture Media

Liquid medium designed to encourage the growth of small numbers of a particular organism while suppressing other flora present

Antimicrobial Susceptibility Testing

Microbiology Procedure

Procedure to determine if a specific microbe is susceptible or resistent to a panel of antimicrobial drugs

Performed on bacteria and fungi isolated from clinical specimens to determine which antimicrobial agents might be effective in treating infections caused by these organisms

Immunohematology

Specialized Area of Medical Technology

Refers to the serologic, genetic, biochemical, and molecular study of antigens associated with membrane structures on the cellular constituents of blood, as well as the immunologic properties and reactions of blood components and constituents

Blood Bank/Center

Immunohematology

Laboratory or institution with the capability to recruit and screen blood donors, collect, process, store, transport, and issue blood for transfusion and provide information and/or education on blood transfusion transmissible diseases

Hospital-based Blood Bank

Immunohematology

Blood bank located within the premises of a hospital and which can perform compatibility testing of blood

Blood Collection Unit

Immunohematology

Institution or facility duly authorized by the Department of Health to recruit and screen donors and collect blood

Voluntary Blood Donor

Immunohematology

One who donates blood on one’s own volition or initiative and without monetary compensation

Nutrient Agar

Specific Types of Culture Media - General Purpose

General-purpose culture media for growing variety of non-fastidious bacteria

Blood Agar

Specific Types of Culture Media - Enriched & Differential

Enriched medium containing 5% sheep/horse blood to grow nonfastidious and fastidious microorganisms (pathogenic bacteria)

Used to observe hemolysis

Chocolate Agar

Specific Types of Culture Media - Enriched

Enriched medium containing lysed RBCs broken down by heat to grow the most fastidious microorganisms

MacConkey Agar (MAC)

Specific Types of Culture Media - Selective & Differential

Selects for Gram-negative bacteria

Differentiates based on lactose fermentation

Eosin Methylene Blue (EMB) Agar

Specific Types of Culture Media - Selective & Differential

Selects for Gram-negative bacteria

Differentiates based on lactose and sucrose fermentation

Xylose Lysine Deoxycholate (XLD) Agar

Specific Types of Culture Media - Highly Selective & Differential

Selective for the isolation of Salmonella and Shigella species

Differentiates those species from other Gram-negative bacteria

Mueller-Hinton Agar

Antimicrobial Susceptibility Testing

Medium used

ABO Typing

Immunohematology Test

Determines the ABO type of an individual

Forward ABO Typing

Immunohematology Test

Detects an unknown antigen on the red blood cell using known commercial anti-Sera

Reverse ABO Typing

Immunohematology Test

Detects unknown naturally occurring antibodies in plasma using known commercial antigens

Gel Technology

Immunohematology Test

Agglutination test based on controlled centrifugation of RBCs through a dextran-acrylamide gel that contains predispensed reagents