Transcript Coagulation disorder

Lecture NO- 12Dr: Dalia Kamal Eldien
 Coagulation:
Is the process by which blood changes from a liquid to a
clot. Coagulation begins after an injury occur to the blood
vessel, causing damage the endothelium lining the vessel. It
results in hemostasis
 Hemostasis:
The cessation of blood loss from a damaged vessel,
followed by repair, the opposite of hemostasis
is hemorrhage.
 Blood coagulation involving both a cellular (platelet) and
a protein (coagulation factor) component
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Hemostasis comprises major events that occur in a set order following the
loss of vascular integrity
The initial phase of the process is vascular constriction. This limits the flow
of blood to the area of injury.
Next, platelets become activated by thrombin and aggregate at the site of
injury, forming a temporary, loose platelet plug.
The protein fibrinogen is primarily responsible for stimulating platelet
clumping, Platelets clump by binding to collagen that becomes exposed
following rupture of the endothelial lining of vessels adhesion , activated
platelets change their shape to accommodate the formation of the plugs.
To insure stability of the initially loose platelet plug, a fibrin mesh (also
called the clot) forms and entraps the plug. If the plug contains only
platelets it is termed a white thrombus; if red blood cells are present it is
called a red thrombus
Platelets plug at the site of injury is called primary hemostasis. Secondary
hemostasis occurs simultaneously
 It
is involves 12 coagulation factors (designated by Roman
numerals as factors I through XII) found in blood plasma
and several other blood components. The factors include
prothrombin, thrombin, and fibrin, each has a precise role
in coagulation, respond in a complex cascade to
form fibrin entraps, which strengthen the platelet plug.
 Thrombin converts Fibrinogen(soluble protein) to Fibrin
monomers(insoluble strands) which polymerize to form a
Fibrin clot.
 The Fibrin clot acts with activated platelets at the site of
the injury to form a blood clot that stabilizes the damaged
tissue and prevents further blood loss.
 Several coagulation cascade models have been
proposed, including the intrinsic and extrinsic pathway
 In
addition to directly generating active Fibrin,
Thrombin activates Coagulation Factor XIII, which
stabilizes Fibrin and promotes its polymerization.
 Thrombin also activates Coagulation Factors V, VIII,
and Protein C. These factors enhance or inhibit
Thrombin production through positive or negative
feedback.
 Finally, the clot must be dissolved in order for
normal blood flow to resume following tissue repair.
The dissolution of the clot occurs through the action
of plasmin
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A deficiency in clotting factors or a disorder that affects
platelet production or one of the many steps in the entire
process can disrupt clotting and severely complicate blood
loss from injury, childbirth , surgery, and specific diseases or
conditions in which bleeding can occur.
Definition:
 Coagulation disorders deal with disruption of the body's abili
ty to control blood clotting.
 When you get injured, your blood normally begins to clot to
prevent a massive loss of blood. Sometimes the mechanism
that causes the blood to clot fails, resulting in rapid or
prolonged bleeding (hemorrhage ) or obstructive clotting
(thrombosis).
 The most commonly known coagulation disorder is
hemophilia, a condition in which patients bleed for long
periods of time before clotting.
There are other coagulation disorders with a variety of causes.
Many causes are related to protein defects in the
plasma . In some diseases, these proteins might be
missing completely or they may be low in concentration.
The majority of these defects are hereditary (passed
from parent to child through genes). However, some
may develop due to other medical conditions.
 Liver disease
 Low red blood cell count
 Vitamin K deficiency
 Medication side-effects
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The most common inherited bleeding disorders are:
1- Hemophilia : caused by a deficiency or lack of certain blood clotting
factors, this disorder causes heavy or unusual bleeding
 If you have hemophilia, you may bleed for a longer time after an
injury than if your blood clotted normally.
 Small cuts usually aren't much of a problem. The greater health
concern is deep bleeding inside the body, especially in knees,
ankles and elbows. That internal bleeding can damage the organs
and tissues, and may be life-threatening.
 Haemophilia A (clotting factor VIII deficiency) and represents 80%
of haemophilia cases
 Haemophilia B (factor IX deficiency)
 hemophilia is
genetic disorder is carried by females but most often affects males
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2- Von Willebrand’s disease: the most common inherited
bleeding disorder; caused by a deficiency of von Willebrand
factor, which helps blood platelets clump together and stick
to a blood vessel wall
3- Disseminated intravascular coagulation . This disease
accelerates clotting, which can actually cause hemorrhage.
4- Thrombocytopenia is the most common cause of
coagulation disorder. It is characterized by a lack of circulating
platelets in the blood.
This disease also includes idiopathic thrombocytopenia.
5- Factor II, V, VII, X, XII deficiency: relate to blood clotting
problems or abnormal bleeding problems
The main sign of a bleeding disorder is prolonged or
excessive bleeding. The bleeding is normally heavier than
normal and unprovoked. Other signs of a bleeding
disorder include:
 unexplained bruising
 heavy menstrual bleeding
 frequent nosebleeds
 Complete
blood count (CBC): to check the amount of
blood loss as well as the amount of red and white blood
cells .
 Platelet Count
 platelet aggregation test
 Bleeding time: to see how fast your blood vessels close
to prevent bleeding
 Clotting time
 Prothrombin Time
(PT) : test measures how well and
how long it takes your blood to clot. It normally takes
about 25 to 30 seconds. It may take longer if you take
blood thinners. Other reasons for abnormal results
include hemophilia, liver disease, and male absorption.
It is also useful in monitoring those who take
medications that affect clotting such as warfarin.
 Fibrinogen Level: Fibrinogen is a protein made by the
liver. Abnormal results may be a sign of hemorrhage,
fibrinolysis, or placental abruption (separation from the
uterine wall).
 Thrombin Time: measures how well fibrinogen is
working. Abnormal results may be due to inherited
fibrinogen disorders, liver disease, some cancers, and
medications that affect clotting.
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