42 Questions
What percentage of blood is composed of formed elements?
45%
Which of the following is NOT a function of erythrocytes?
Defense against foreign antigens
What is the primary function of leucocytes?
Defense against foreign antigens
What is the function of platelets in the blood?
Formation of blood clots
What is the term for the study of blood?
Haematology
What is the term for the process of stopping bleeding at an injured site?
Haemostasis
What is the term for a disorder involving the production of haemoglobin?
Haemoglobinopathy
What is the percentage of plasma in the blood?
55%
What is the purpose of anticoagulants in haematology tests?
To prevent blood clotting
What is the main component of plasma in terms of percentage?
Water (90-92%)
Which of the following laboratory tests measures the deviations of blood constituents from normal values?
All of the above
What is the importance of the proper proportion of anticoagulant to whole blood in haematology tests?
To avoid errors in test results
Why is EDTA commonly used as an anticoagulant in haematology tests?
Because it does not distort blood cells
What is the purpose of using different colored tubes in blood collection?
To add different anticoagulants depending on the test being performed
What factors can influence normal values of formed cellular elements in blood?
Age, sex, and geographic location
What is the characteristic of an anticoagulant used in haematology tests?
It does not alter the size of blood cells and minimizes platelet aggregation
What is the primary role of a phlebotomist?
To draw blood for laboratory tests or blood donations
What is the minimum amount of blood sample typically required for blood tests?
5 ml
Why should blood never be poured from one tube to another?
Because the tubes can have different additives or coatings
What is the purpose of a tourniquet in venipuncture?
To restrict blood flow to the area
What is the recommended percentage of isopropyl alcohol in alcohol wipes?
70%
What is the primary function of lithium heparin in a Plasma Separating Tube (PST)?
To anticoagulate with heparin and separate plasma with PST gel
Why should the finger or heel be punctured across the fingerprints in capillary puncture?
To make the blood more likely to bead rather than run down the channels
Which anticoagulant is used for Coagulation tests, such as PT and APTT?
Sodium citrate
What is the purpose of Sodium fluoride and potassium oxalate in blood collection tubes?
To preserve glucose up to 5 days
What is the importance of puncturing only within the designated areas in infant skin puncture?
To prevent neurological or soft tissue damage
What must accompany each sample submitted to the laboratory?
A requisition form
Which additive is used for Hematology tests, such as FBC/CBC and Blood Bank (Crossmatch)?
EDTA
What is the mode of action of Sodium citrate in blood collection tubes?
Forms calcium salts to remove calcium ions
Which anticoagulant is used for Serum lead determination?
Sodium heparin
What is the purpose of Thrombin in blood collection tubes?
To quickly clot blood
Which additive is used for HLA tissue typing, paternity testing, and DNA studies?
ACD (acid-citrate-dextrose)
What is the primary function of Potassium EDTA (K2/K3) in blood collection tubes?
To form calcium salts and remove calcium ions
What is the process of obtaining a sample of venous blood called?
Phlebotomy
What is the main purpose of a requisition form?
To provide essential information for processing the specimen
What information is required when requesting microbiology, cytology, or fluid analysis?
All of the above
What happens to a clotted specimen?
It is rejected and not processed
Why is it important to follow safety and infection control procedures?
To protect oneself from contact with sick patients and their specimens
What should you do if you stick yourself with a contaminated needle?
All of the above
What should be done with needles immediately after removal from the patient's vein?
They should be disposed of immediately
What should be used to clean up blood spills?
Freshly made 10% bleach
What should you do after handling blood/body fluids?
All of the above
Study Notes
Introduction to Haematology
- Haematology is the study of blood, composed of plasma (~55%) and the formed elements (erythrocytes, leucocytes, and platelets)
- Alterations in the formed elements are often the first sign of disease in the body
- Laboratory tests measure deviations in blood constituents from normal values
Blood Composition
- Plasma: 90-92% water, 6-7% proteins, 2-3% fats, carbohydrates, electrolytes, and gases (O2, CO2)
Anticoagulants in Haematology
- Anticoagulants prevent blood clotting and are used in haematology tests
- Characteristics of anticoagulants: do not alter cell size, do not cause haemolysis, minimize platelet aggregation, and do not disrupt staining and morphology of blood cells
- Common anticoagulants used: EDTA, sodium citrate, and heparin
- EDTA is commonly used because it does not distort blood cells
- The proper proportion of anticoagulant to whole blood is important to avoid errors in test results
Blood Collection Tubes
- Different tubes are used for different tests, each with its own additive
- Additives and their uses:
- EDTA: haematology tests (FBC/CBC) and blood bank (crossmatch)
- Sodium citrate: coagulation tests (PT, APTT)
- Sodium heparin: lithium level, ammonia level, and serum lead determination
- Lithium heparin: chemistry tests
- Thrombin: STAT serum chemistries
- Sodium fluoride and potassium oxalate: glucose tests
- ACD (acid-citrate-dextrose): HLA tissue typing, paternity testing, and DNA studies
Phlebotomy
- Phlebotomy is the process of obtaining a sample of venous blood
- A phlebotomist is an individual trained to draw blood for laboratory tests or blood donations
- Equipment needed for routine venipuncture:
- Evacuated collection tubes
- Needles/tube holder/syringes/butterfly system
- Tourniquet
- Alcohol wipes
- Gauze sponges
- Adhesive bandages/tape
- Gloves
Capillary Puncture
- Perform finger or heel puncture across the fingerprints
- For infants or neonates, puncture only within designated areas on the heel to avoid neurological or soft tissue damage
Order Form/Requisition
- A requisition form must accompany each sample submitted to the laboratory
- Essential elements of the requisition form:
- Patient's name
- Patient's ID number
- Patient's date of birth and sex
- Requesting physician's complete name
- Source of specimen
- Date and time of collection
- Tests requested
Rejection of Unacceptable Specimen
- Reasons for rejecting a specimen:
- Clotted specimen
- Severely hemolyzed specimen
- Improperly labelled or unlabelled specimen
- Specimen too old
- Failure to meet volume criteria
- Improperly collected specimen
- Leaking tube
- Delay in transport
- Collection of specimen in wrong tube
Safety and Infection Control
- Practice universal precautions to protect yourself and others
- Wear gloves and a lab coat or gown when handling blood/body fluids
- Change gloves after each patient or when contaminated
- Wash hands frequently
- Dispose of items in appropriate containers
- Dispose of needles immediately upon removal from the patient's vein
- Follow institution's guidelines regarding treatment and follow-up if stuck with a contaminated needle
This quiz introduces the basics of haematology, covering topics such as haematopoiesis and its regulation. It is a foundational course for students of health sciences and biomedicine.
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