Haemostasis is the process of preventing and stopping bleeding by keeping blood within damaged blood vessels. It involves three main stages: 1) vasoconstriction of the damaged vessel, 2) formation of a platelet plug through primary haemostasis, and 3) formation of a fibrin clot through the coagulation cascade. The integrity of haemostasis depends on the vessel wall, platelets, and coagulation factors. Low platelet production or platelet dysfunction can lead to thrombocytopenia and bleeding, while deficiencies in coagulation factors cause bleeding into tissues through the coagulation cascade. Diseases like liver disease or disorders like disseminated intravascular coagulation can also impair haemostasis.

1. Haemostasis
haemostasis is a process to prevent and
stop bleeding, meaning to keep blood
within a damaged blood vessel.
Stages
1. Vasoconstriction
2.primary haemostasis

2. Haemostasis Pathway
Injury
Primary haemostasis sec: haemostasis
Collagen exposure
Platelet adhesion Coagulation Cascade
Release reaction
Platelet aggregation Fibrin
Primary haemo: plug Sec: Haemo: Plug

3. Integrity of Haemostasis
Depends on:
1. Vessel wall
2. Platelets (no. and function)
3. Coagulation factors

4. Primary haemostasis

5. Vessel Wall
• Release tissue factor that initiates
coagulation cascade.
• Exposed collagen results in platelet
adhesion (using vWF as a bridge).
• That leads to platelet plug formation and
stop the bleeding temporarily

6. Thrombocytopenia
Causes
Low production of platelets (aplastic)
increase consumption of Platelets(DIC)
Increase destruction of platelets(ITP,
TTP)

7. Low Platelet production
• N = 150 – 450k
• Excessive bleed / Spontaneous bleed(nose, mouth
andsmall cut bleeding)
• Mucosal surfaces / Skin (petechiae & ecchymosis)
• Immune Mediated Thrombocytopenia
• Drug induced(chloramphenicol)
• Haemolytic Uraemic Syndrome

8. Platelet Dysfunction
• Abnormal platelet aggregation
• Normal platelet count
• Excessive / spontaneous bleed
• Mucosa / Skin
• Inherited disorders
• Drug induced

9. Secondary
haemostasis
Coagulation cascade begins

10. Eccymoses

12. Coagulation Factors Deficiency
• Spontaneous bleeding into deep tissues
• Increased post-traumatic haemorrhage
• Factor 8 – Haemophilia A
• Factor 7 – Haemophilia B
• vWF – Von Willebrand’s disease
Von Willebrand’s Factor:
• Protein produced by endothelial cells which mediates
platelet adhesion to endothelium and carries factor 8 in
plasma.

13. Haemoarthroses

14. Other causes of
factors Def:

15. Liver Disease
• Mixed – both coag deficiency and platelet
problem
• Reduced coag factor synthesis
(1, 2, 5, 7, 9, 10)
• Cirrhosis  Hypersplenism 
Thrombocytopenia

17. Drug Induced Coag Factor Def
Heparin:
• Inactivates certain coag factors (e.g. 9a,
10a, 11a, 2)
• Also impairs platelet function
Warfarin:
• Block synthesis of Vit K dependent factors
(2, 7, 9, 10)

18. DIC
Causes of coag cascade activation:
1. Sepsis
2. Disseminated cancer
3. Obstetric complications (e.g. retained product of
conception)
4. Fulminant liver disease
5. Anaphylaxis
6. AML

19. DIC
Consequence of Thrombosis:
1. Tissue infarction  Renal impairment
2. CVA
3. PE
4. DVT
5. Consequence of Bleeding:
6. Purpura
7. GI Bleed

20. Other Disorders
• Vitamin K deficiency
• Autoantibodies to coag factors
• Haemorrhagic disease of the newborn
• Massive transfusion

26. Question
Which one of them is due to
thrombocytopenia and which from
coagulation disorder?

30. PT/iNR. aPTT.
Extrinsic pathway. Intrinsic pathway
FACTOR vii. FACTOR VIII
Common pathway. Common pathway
Factor I,ii,v,x. Factor I,ki,v,x
Warfarin. Heparin

31. Normal range
PT =8.4 - 13.0 sec
APTT= 23-31.4 sec
INR =0.8 - 1.2 sec
Platelets =150 -450k
Fibrinogen= 130- 330 mg/dl
Bleeding time= 2- 6 mints
Clotting time=2- 8 mints

33. Investigations for Bleeding
Condition Test
Wall Defect All tests are normal.
Low Platelet Low platelet count + bleeding time
Platelet Dysf Normal platelet count + bleeding time
Haemophilia APPT
vWD APPT + bleeding time
Liver Disease INR + APPT + platelet count
Drug Induced INR + APPT + plasma level
DIC All tests are abnormal.

38. Thank you All