Indian Dental Academy Leader in Dental Education

INDIAN DENTAL ACADEMY
Leader in continuing Dental
Education
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Haemostatic Mechanism
Haemostasis, a complex process, can be divided into
Primary
• Vasoconstriction
• Platelet adhesion
• Platelet aggregation
• Platelet plug formation
Secondary
• Stabilization of platelet
plug by fibrin network.

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Primary Haemostasis

Secondary haemostasis
(Coagulation of Blood)
The coagulation mechanism is one of the component of
haemostatic mechanism.
It comprises three separate though related systems
1. Coagulation system
2. The coagulation inhibitory system
3. Fibrinolytic system
Pathological disturbances may occur in any or more of
these systems and lead to bleeding tendency or
intravascular coagulation

1. Coagulation system

2. The coagulation inhibitory system
1. Antithrombins
2. Heparin
3. Protein C
4. TFPI (Tissue factor pathway inhibitors)

3. Fibrinolytic mechanism

Principles underlying coagulation tests
Test Principle Causes of abnormality
Blood clotting time Contact activation by
glass tube
Deficiency of intrinsic
pathway
Partial thromboplastin
time
Intrinsic pathway
activated by kaolin
Deficiency of factors-
XII,IX,XI,X,V,VIII
Prothrombin time Extrinsic pathway
activated by brain
tissue.
Deficiency of factors-
VII,X,V,
Thrombin time Fibrinogen is
converted to fibrin by
added thrombin
Deficiency of
fibrinogen or high
level of FDPs
Bleeding time Duration of bleeding
from skin puncture is
timed
Defect in platlets

Classification of Haemorrhagic disorders
1. Defect of the blood vessels
• The vascular purpuras
 Infections-typhus,typhoid,meningococal
meningitis,measles
 Chemical agents-
aspirin,frusemide,phenytoin,indomethacin
 Anaphylactoid purpura
 Metabolic purpura
 Scurvy
• Hereditary haemorrhagic telangiectasia

2. Disorders of the blood platelets
• Reduced no of platelets - idiopathic and secondary
thrombocytopenic purpura
• Increase no of platelets - thrombocytopenia
• Defective platelets - hereditary and acquired
thrombasthenia

3. Disorders of clotting mechanism
• Hereditary
 Haemophilia (A & B)
 Von willebrand’s disease
 Deficiency of other clotting factors.
• Acquired
 Vit-K deficiency
 Anticoagulant therapy
 Disseminated intravsacular coagulation
 Liver disease
 Acute primary fibrinolysis
 Circulating inhibitors of coagulation.www.indiandentalacademy.com

I. Deficiency of one or more blood coagulation factors due to
A. Defective synthesis
B. Excessive utilization with normal synthesis
- Defective synthesis of plasma coagulation factor may occur due to
1. Genetic cause usually cause deficiency of single coagulation
factor.
2. Deficiency of Vit-K.
3. Severe disease of the liver.
- Excessive utilization of the clotting factor may occur due to one of
the following condition.
1. Defibrination syndrome
2. Pathological fibrinolysis

• Inhibition of coagulation
Change in naturally occurring inhibitors do not cause pathological
condition. But in certain circumstances abnormal inhibitors appear
and interfere with blood coagulation.
• Fibrinolysis
In certain circumstances the fibrinolytic system may be
pathologically activated

Factor VIIIVon willebrand complex

HAEMOPHILIA - A
- Haemophilia is a congenital haemorrhagic disorder
with sex-linked inheritance occurring almost
exclusively in males
- 20% to 30% pts have no family history of disorder
- Incidence
1 per 10,000 males.

The females carrying a gene for haemophilia on one of their two X-
chromosomes transmit the gene to half of their female offspring and half
of their male offspring.

Haemophiliacs having only one X-cromosome transmit the gene to all
their female offspring but none of their male offspring

Pathophysiology
•Factor VIII:C absent or
reduced
•Factor VIIIR:Ag and vWF
activities are present in
normal amount
•As a result of defect in factor
VIII intrinsic pathway of
coagulation is defective.

Severity of the bleeding
Factor VIII Severity of FeaturesFactor VIII Severity of Features
level- haemophilialevel- haemophilia
50 – 200% (Normal factor VIII level.)50 – 200% (Normal factor VIII level.)
25%25% - Min conc for- Min conc for
haemostasis.haemostasis.
5 – 25 %5 – 25 % Mild - Major injury resultsMild - Major injury results
in bleedingin bleeding
2 – 10 % Moderate - Mild injury results in2 – 10 % Moderate - Mild injury results in
bleedingbleeding
Less than 2 % Severe - Hemarthrosis andLess than 2 % Severe - Hemarthrosis and
hematomashematomaswww.indiandentalacademy.com

Variability of the bleeding tendency
• During the period of an increase tendency to bleed
patients experience bleeding into the tissues following
the slightest injury and may even bleed spontaneously.
• During the phase of reduce tendency to bleed they
can withstand quite severe contusions without ill
effects.

Type and site of the bleeding
1. Wound bleeding
• Characteristic symptom of all haemophilics.
• Excessive bleeding from extraction socket is one of the most
diagnostic sign as it is present even mild haemophilics.
2. Joints & Bones
• Haemarthrosis of the knee joint is common.
• Intraarticular adhesion of the joint.
• Destruction of the cartilage
• Intraosseous haemorrhage may cause bone necrosis and cyst
formation
• Long term joint damage may develop osteo-arthritic changes marked
by loss of joint space ,sclerosis,atrophy of the muscles &www.indiandentalacademy.com

Bone cyst
Haemarthrosis of knee
joint

Atrophy of muscles
Claw hand deformity of hand

Osteoporosis of
knee joint

3. Bleeding into muscle my lead to degeneration and
contracture of the muscle.
4. Compression of the peripheral nerve by large haematoma
may cause peripheral nerve lesions
5. Haemophilic cysts and pseudotumour is common
particularly in pelvic and knee region which progressively
enlarge and sometime erode through skin and cause
ulceration on the skin.
6. Haematuria is common in severe haemphilia. Bilateral
obstruction by clots causes acute oliguric renal pain.
7. Spontaneous intracranial and intraspinal haemorrhage is
common in severe haemophilic.

Haemophilia – B
(Christmas Disease)
Christmas disease is a congenital sex-linked haemorrhagic disorder due
to absence,reduction or functional abnormality of factor IX
Incidence
1 per 50,000 male
Clinical features are same as Haemolhilia – A
Pathophysiology
Factor IX coagulation activities is reduced or absent.

Von-Willebrand’s disease
It is a autosomally transmitted congenital haemorrhagic disorder in
which there is prolongation of bleeding time in addition to reduction of
factor VIII coagulation activity.
v WFv WF
-A protein synthesized by endothelial cells andA protein synthesized by endothelial cells and
megakaryocytes, performs 2 functionsmegakaryocytes, performs 2 functions
1. acts as carrier protein for factor VIII1. acts as carrier protein for factor VIII
2. forms bridge between platelets and subendothelial2. forms bridge between platelets and subendothelial
components allowing platelets tocomponents allowing platelets to adhere to theadhere to the
vessel wall.vessel wall.

Types
1. Type I – Factor VIIIvWF reduced in quantity but
qualitatively normal.
2. Type II – vWF is not synthesize at all or
functionally abnormal synthesis of vWF.

Clinical features
There is reduction of factor VIII:C so bleeding may occur
as mild form of haemophilia.
1. Mucosal bleeding(epistaxis)
2. Gastrointestinal bleeding
3. Gingival bleeding
4. Menorrhagia

Comparison of Haemophilia & VWD
Mild Haemophilia VWD
Relative incidence Uncommon Moderately uncommon
Sex Male Male or Female
Inheritance Sex linked recessive Autosomal dominant
Ecchymoses Rare Small,frequent
Epistaxis Rare Common
Surgical bleeding Delayed Immediate
Haematomas Common Uncommon
Haemarthrosis Common Uncommon

Other Coagulation factors abnormalities
Factor Inheritance Laboratory
defect
C/F
Factor XII Autosomal
recessive
aPTT,BT,CT
prolonged
Nil
Factor X Autosomal
recessive
aPPT,CT
prolonged
Mild bleeding
Factor VII Autosomal
recessive
Normal aPTT
prolonged PT
Mild bleeding
Factor V Autosomal
recessive
PT and aPTT
prolonged
Mild bleeding
Factor II Autosomal
recessive
PT and aPTT
slightly
prolonged
Mild bleeding
Factor XIII Autosomal
recessive
PT,aPTT,Throm
bin normal
Mild bleeding

Acquired coagulation disorders may occur due to one of
the following causes.
1. Vit-K deficiency
2. Liver diseases
3. Anticoagulant therapy
4. Disseminated intravascular coagulation
5. Acute primary fibrinolysis
6. Circulating inhibitors of coagulation

Vit-K deficiency
 Disorders that impair fat absorption
• Obstructive jaundice and biliary fistula
• Pancreatic disease and related disorders
 Sterilization of bowel by antibiotics
 Haemorrhagic disease of the newborn
• reduced store of Vit-K
• Functional immaturity of liver
• Lack of bacterial synthesis of Vit-K

Disseminated intravascular coagulation
DIC is a syndrome arising as a complication of many different
serious and life-threatening illnesses. In its acute (overt) form
it is a hemorrhagic disorder, characterized by multiple
ecchymoses, mucosal bleeding, and depletion of platelets and
clotting factors in the blood. Chronic DIC, on the other hand,
is more subtle and involves thromboembolism accompanied
by evidence of activation of the coagulation system.

Etiology
1. Infections
Acute DIC: Bacteria and their toxins, fungi, viruses,
Chronic DIC: Any chronic infection (eg, tuberculosis, abscesses,
osteomyelitis)
2. Noninfectious inflammatory diseases
Inflammatory bowel disease: Crohn's disease and similar disorders
3. Obstetrical complications
Acute DIC: Abruptio placentae, abortions ,amniotic fluid embolism,
hemorrhagic shock
Chronic DIC: Dead fetus syndrome

4. Malignancy
Acute DIC: Acute promyelocytic leukemia, acute myelomonocytic or
monocytic leukemia, disseminated prostatic carcinoma
Chronic DIC: Lung, breast, gastrointestinal malignancy
5. Vascular disease
Acute DIC: Brain infarction or hemorrhage
Chronic DIC: Aortic aneurysm, giant hemangioma
6. Venoms
Acute DIC: Snake, spider (rare)
7. Trauma
Acute DIC: Massive tissue destruction, brain damage
8. Others
Acute DIC: Heparin-induced thrombocytopenia with thrombosis (HITT),

Clinical features
 Acute DIC
• Multiple bleeding sites
• Ecchymoses of skin, mucous membranes
• Visceral hemorrhage
• Ischemic tissue
 Chronic DIC
• Signs of deep venous or arterial thrombosis or embolism
• Superficial venous thrombosis, especially without varicose
veins
• Serial thrombotic episodeswww.indiandentalacademy.com

Hemorrhaged small intestine
Hemorrhaged heart

Liver Diseases
The no. of factors may contribute to the haemostatic defect
in liver disease.
1. Defective synthesis of clotting factors
2. Increased fibrinolytic activities
3. Intravascular coagulation.
4. Hepatitis.
5. Malabsorption of Vit-K due to parenchymatous diseases.

Anticoagulant Drugs
Most commonly used anticoagulant dtugs are heparin and Vit-K
antagonists.
Bleeding during anticoagulant therapy may be due to.
1. Overdose
2. To a local lesion. Commonly result from minor trauma e.g.
intramuscular injection.
• Increased susceptibility
Serious spontaneous bleeding most commonly occurs when an
anticoagulant drug is given in the usual therapeutic dose to a patient
with increase susceptibility.

Factors influencing susceptibility of the patient to
anticoagulant drug.
Drugs
Potentiating Inhibitory
1. Salicylate
2. Phenylbutazone
3. Sulphonamides
4. Thyroxine
5. Oxymetholone
1. Barbiturates
2. Chloral hydrate
3. Spironolactone
4. Glutethimide

Other factors
Potentiating Inhibitory
1. Diarrhoea
2. Alcohol
3. Hepatitis
4. Acute renal
failure
1. Hereditary
2. Resistance

Haemorrhage and Blood transfusion
Haemorrhage resulting from blood transfusion may be due to
1. Administration of large amount of stored blood.
2. Haemolytic transfusion reaction.
3. Transfusion thrombocytopenia due to platelet allo-
antibodies.

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