Basic Haematological Techniques-II Notes
Subject Overview
Basic Haematological Techniques-II moves from cell counting into haemoglobin chemistry and coagulation — normal and abnormal haemoglobin pigments and their measurement, the normal haemostatic mechanism and theories of blood coagulation, classification and properties of the coagulation factors, and the screening tests used to investigate bleeding disorders (bleeding/
Subject at a glance
3
Units
9
Topics
4
Credits
3
Infographics
Unit-wise Syllabus
3 units — open any unit for detailed topic-wise notes, diagrams and important exam questions
Haemoglobin pigments and their measurement, abnormal haemoglobins — identification and estimation
Oxyhaemoglobin
Hb carrying oxygen
Bright red
Methaemoglobin
Iron in the ferric (Fe³⁺) state
Can't carry oxygen; some drugs and nitrites
Carboxyhaemoglobin
Hb bound to carbon monoxide
CO poisoning: cherry-red colour
Sulphaemoglobin
Sulphur bound to Hb
Irreversible; some drugs
Study guide
This unit covers haemoglobin chemistry: the pigments and their measurement, and the identification and estimation of abnormal haemoglobins. Learn the normal types of haemoglobin and the common variants such as HbS and HbF.
- Normal haemostatic mechanism and theories of blood coagulation
- classification of coagulation factors
- physiological properties of coagulation factors
- 1Intrinsic pathway
Factors XII, XI, IX, VIII: tested by APTT
- 2Extrinsic pathway
Tissue factor and factor VII: tested by PT
- 3Common pathway
Factors X, V, II (prothrombin)
- 4Thrombin forms
- 5Fibrinogen to fibrin
Stable clot with factor XIII
Study guide
You study how the body stops bleeding: the normal haemostatic mechanism, theories of blood coagulation, the classification of coagulation factors and their properties. Learn the coagulation cascade as a flow diagram with the intrinsic, extrinsic and common pathways.
- Bleeding time and clotting time
- Hess test
- prothrombin time (PT)
- activated partial thromboplastin time (APTT)
Bleeding time (Duke / Ivy)
2–7 min
Platelet disorders, von Willebrand disease
Clotting time
4–9 min (Lee-White)
Severe factor deficiencies
PT
11–16 sec (lab-specific)
Warfarin therapy, liver disease, vitamin K deficiency
APTT
25–40 sec (lab-specific)
Haemophilia A and B, heparin therapy
Study guide
You study screening tests of coagulation: bleeding time, clotting time, the Hess test, prothrombin time (PT) and activated partial thromboplastin time (APTT). Know which pathway each test assesses and what a prolonged result suggests.
Why Basic Haematological Techniques-II Matters
Coagulation tests such as PT and APTT are among the most requested hospital tests, used to monitor anticoagulant therapy and to investigate bleeding disorders before surgery.
How to Prepare for Basic Haematological Techniques-II
- Draw the coagulation cascade and mark where PT and APTT measure.
- Learn the normal values of each test.
- Understand why each test's sample handling (citrate, timing) matters.
Basic Haematological Techniques-II: Frequently Asked Questions
What do PT and APTT measure?
PT assesses the extrinsic and common pathways of coagulation, while APTT assesses the intrinsic and common pathways.
What is haemostasis?
Haemostasis is the process by which the body stops bleeding by forming a blood clot at the site of injury.