DEFINITION FACTORS INVOLVED IN BLOOD CLOTTING SEQUENCE OF CLOTTING MECHANISM BLOOD CLOT ANTICLOTTING MECHANISM IN THE BODY ANTICOAGULANTS PHYSICAL METHODS TO PREVENT BLOOD CLOTTING PROCOAGULANTS TESTS FOR BLOOD CLOTTING APPLIED PHYSIOLOGY

1. Coagulation Profile
Pandian M
Department of Physiology
D. Y. Patil Medical College, Kolhapur

2. Slo’s
• DEFINITION
• FACTORS INVOLVED IN BLOOD CLOTTING
• SEQUENCE OF CLOTTING MECHANISM
• BLOOD CLOT
• ANTICLOTTING MECHANISM IN THE BODY
• ANTICOAGULANTS
• PHYSICAL METHODS TO PREVENT BLOOD CLOTTING
• PROCOAGULANTS
• TESTS FOR BLOOD CLOTTING
• APPLIED PHYSIOLOGY

3. Introduction
• This tests are determined to assess the integrity of haemostatic
mechanism.
HAEMOSTASIS –
Spontaneous arrest or prevention of bleeding by
physiological process is called haemostasis.

4. Series of events involved in haemostasis

5. Bleeding Time
• Bleeding time is defined as time interval between puncture to the
blood vessel to the stoppage of bleeding.
Methods of determination of bleeding time-
I) Duke Method
II) Ivy Method

6. Duke Method
[ 30 sec interval ]
5 blots (4 blood blots+ 1 blank blot) x 30 sec = 2mins 30 sec

7. Ivy Method

8. Clotting Time
• Clotting time is defined as time interval between puncture to the
blood vessel to the formation of fibrin thread.
Methods of determination of clotting time-
I) Capillary tube method
II) Lee - White method

9. Capillary tube method
iv
i ii iii

11. Lee - White method
Principle
Venous blood is collected in clean glass tube without any anticoagulant.
The time taken by blood to clot at 37 degree Celsius is noted as clotting
time.
Normal Value – 5 to 12 minutes
Clinical Significance
This method is more reliable than the capillary tube method. The
clinical significance of this method is the same as that of capillary tube
method

12. Conditions where BT & CT are altered
Bleeding time is prolonged in :
i) Thrombocytopenia - ↓ in platelet count
ii) Thrombasthenia – Platelet count is normal but they are functionally
abnormal
iii) Von Willebrand disease – Platelet defect combined with factor VIII
deficiency.
iv) Purpura – It is a condition with various manifestation & different
causes, characterized by capillary abnormality resulting in
haemorrhages into the skin, mucous membrane, internal organ &
other tissues.

13. Clotting time is prolonged in :
i) Classical Haemophilia (Haemophilia A)
ii) Vitamin K deficiency
iii) Christmas disease
iv) Liver diseases – Hepatitis, cirrhosis
v) Anticoagulant overdose

14. Clinical significance of determining BT & CT
It is very important to know BT & CT in the following conditions :
i) Before surgery
ii) Before any biopsy, especially liver or bone marrow biopsy
iii) Before putting any patient on anticoagulant therapy

15. Other tests for bleeding disorders
Capillary Fragility Test
Principle
This test measures the ability of the capillaries to withstand increased
stress. petechiae appear in the forearm of the subject when the blood
pressure cuff in the arm is inflated to a maximum pressure of 100mm
Hg for about 5 minutes.
Clinical Significance
Normally,0-10 petechiae appear. More them 10 petechiae indicates
capillary weakness, thrombo-cytopenia or both.

16. Platelet Aggregation Test
Principle
An aggregating agent is added to a suspension of platelets in plasma
and the response is measured turbidometrically as a change in the
transmission of light by an instrument called the aggregometer.
Clinical Significance
Measurement of platelet aggregation is an essential part of the
investigation of any patient with suspected platelet dysfunction.

17. Platelet Adhesiveness Test
Principle
This test measures the ability of platelets to adhere to a glass surface.
When anticoagulated blood is allowed to pass at a constant rate
through a plastic tube containing glass beads, some platelets adhere to
the glass beads. The percentage difference of the platelet count prior
to & after passing through the glass bead column indicates the
functional status of platelets.
Clinical Significance
The normal range is 75%-95% of platelet retention. The platelet
adhesiveness test is non specific. The results are abnormal in several
platelet functional disorders

18. Clot Retraction Time
Principle
Blood clots when collected in a glass tube without any anticoagulant.
The clot begins to retract (after blood has clotted) within 30 seconds, &
about 50% at the end of 1 hour. At the end 18-24 hours the clot should
have retracted completely.
Clinical Significance
Abnormal clot retraction is reported when less than 50% retraction
occurs at 1 hour. Clot retraction is primarily dependent on platelet
function. Hematocrit & fibrinogen level also affect it. Poor clot
retractability is usually seen when platelet count is less than 1,00,000.

19. Clot Lysis Time
Principle
The clot is lysed due to fibrinolysis, which is a natural process. Due to
lysis the clot becomes fluid & red cells sink to the bottom of the test
tube.
Clinical Significance
The lysis time for the normal clot is about 72 hours. If lysis is seen
within 24 hours, fibrinolysis is considered to be abnormal.

20. Prothrombin Consumption Test
Principle
This test determines the amount of prothrombin present in the serum
after clot formation.
Clinical Significance
Normally, in the coagulation process more than 95% of prothrombin is
used up as it is converted to thrombin. The presence of more than 5%
of prothrombin in the serum indicates a quantitative or qualitative
platelet deficiency

21. Prothrombin Time (PT)
Principle
A preparation of rabbit brain emulsion (which contains tissue
thromboplastin) is added to plasma in the presence of calcium. This, in
the presence of factor VII triggers stage 2 of the coagulation
mechanism, & the clotting time is recorded after the addition of
calcified thromboplastin to the plasma
Normal Value - 12-16 seconds
Clinical Significance
Prolonged PT suggest the possibility of deficiency of factor II, V, VII, X.

22. Partial Thromboplastin Time (PTT)
Principle
The platelet substitute, in the form of partial thromboplastin, is
prepared from rabbit brain as chloroform extract. When mixed with
test plasma containing excess of calcium, it leads to clot formation.
Normal Value - 60 to 80 seconds
Clinical Significance
PTT is prolonged when there is deficiency of one or more clotting
factors XII, XI, X, IX, VIII, V, II & I.

23. Activated Partial Thromboplastin Time (APTT)
Principle
The platelet substitute, in the form of partial thromboplastin is
prepared from rabbit brain. This is incubated with a contacting agent
(kaolin) to provide optimal activation of the intrinsic coagulation
factors. The clotting time is determined after the addition of excess of
calcium.
Normal Value – 25 to 40 seconds
Clinical Significance
APTT is prolonged in deficiencies of factor XII, XI, X, IX & VIII.

24. Thrombin Time (TT)
Principle
Thrombin (commercially available) is added to the plasma along with
calcium & the clotting time is determined.
Normal Value – 15-20 seconds
Clinical Significance
Thrombin time detects the effectiveness of the stage 3 of coagulation
in which fibrinogen is converted to fibrin. A prolonged TT is considered
to be due to either a decrease in fibrinogen or the presence of
dysfunctional fibrinogen.

25. Plasma Recalcification Time (PRT)
Principle
When excess of calcium is added to the citrated plasma, clotting
occurs. Because platelet factor III is also involved in clotting through the
intrinsic pathway of coagulation, the clotting occurs in a shorter time in
platelet rich plasma than in platelet poor plasma.
Normal Value –
Platelet rich plasma - 100 to 150 seconds
Platelet poor plasma – 135 to 240 seconds
Clinical Significance
This is an easy screening test that detects the deficiency of the factor of
the intrinsic pathway, that is, factors XII, XI, X, IX, V & II.

27. Referred :-
• Text book of Medical Physiology
• Guyton, 13th edition,
• Text book of Medical Physiology
• Indu khurana,
• Text book of Medical Physiology
• Vander’s
• Text book of Medical Physiology
• Sembulingam &
• LPR

28. Thank You