Chapter 5

1. 5- HEMORRHAGIC DISEASES OF
THE NEWBORN
By Eyayalem M
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2. Definition
• It is an accentuation of the normal deficiency
of vitamin K for a longer period.
• A moderate decrease of vitamin K dependent
clotting factors[II, VII, IX, and X] normally
occurs in all newborn infants by 48-72 hours
after birth with gradual return to birth levels
by 7-10 days of life.
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3. WHAT CONDITIONS CAUSE HEMORRHAGIC
DISEASE?
A) Congenital absence of coagulation factors
• e.g. Hemophilia (Factor VIII deficiency)
caused by a gene in X-chromosome which
result in a profound depression of the level of
factorVIII.
- In this case hematoma after injection and
bleeding of circumcision is common
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4. WHAT CONDITIONS CAUSE
HEMORRHAGIC DISEASE?
B) Acquired coagulation disturbance
The chief causes of hemorrhagic disorders in the new
born are:-
• Vit. K deficiency(lack of free vitamin K in the mother)
• Thrombocytopenia
• absence of bacterial intestinal flora
• Disseminated intravascular coagulation
• Deficiency of other clothing factors
• limited storage in the liver
• Breast milk is a poor source of vitamin K.
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5. 5
Haemostasis
 The term hemostasis means prevention of
blood loss.
 Hemostasis is the process of forming clots in the walls
of damaged blood vessels and preventing blood loss,
while maintaining blood in a fluid state within the
vascular system.

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Mechanism
Hemostasis involves 4 main steps:
1. Vascular spasm
2. Platelets reaction
3. Formation of platelet plug
3. Blood coagulation

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I-Vascular spasm
Reduces flow of blood from injured vessel.
Cause:
1- Sympathetic reflex
2- Release of vasoconstrictors (TXA2 and
serotonin) from platelets that adhere to the
walls of damaged vessels.

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II- Platelet plug formation
Mechanism:
Platelet adherence
Platelet activation
Platelet aggregation

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Platelets
• Produced in the bone marrow by fragmentation of the
cytoplasm of megakaryocytes (1000-5000/cell).
• 1/3 of marrow output of platelets is trapped in spleen
(splenectomy?)
• Normal count: 150,000-400,000/µL (250,000)
• Life span 7-10 days.
• Removed from circulation by tissue macrophage system
mainly in spleen.
• Thrombopoietin: major regulator of platelet production
(produced by liver and kidney).
• It increases no. & rate of maturation of megakaryocytes.

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Functional characteristics of
platelets
• The cell membrane of platelets contains:
– A coat of glycoprotein (receptors) that cause
adherence to injured endothelial cells and
exposed collagen.
– Phospholipids, that play an important role in
blood clotting.

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Mechanism of platelet plug formation
* Platelet adhesion: When a blood vessel wall is
injured, platelets adhere to the exposed
collagen and von Willebrand factor in the wall
via platelet receptors → Platelet activation.
*Activated platelets release the contents of their
granules including ADP and secrete TXA2 →
activates nearby platelets to produce further
accumulation of more platelets (platelet
aggregation) and forming a platelet plug.

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Blood Coagulation
The clotting mechanism involves a cascade of
reactions in which clotting factors are activated.
Most of them are plasma proteins synthesized by
the liver (vitamin K is needed for the synthesis of
factor II, VII, IX and X).
They are always present in the plasma in an
inactive form.
When activated they act as proteolytic enzymes
which activate other inactive enzymes.
Several of these steps require Ca++ and platelet
phospholipid.

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Intrinsic pathway
 The intrinsic pathway begins with the contact
factors, factor XII, HMWK, and prekallikrein,
which activates factor XI.
 Activated factor XI can then activate factor IX,
which then acts with its cofactor,factor VIII,to
form tenase complex on a phospholipid surface
to activate factor X.
 Activated factor X then combines with its
cofactor, factor V, to form the prothrombinase
complex on a phospholipid surface, converting
prothrombin to thrombin.

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Intrinsic pathway
 The initial reaction is the conversion of inactive
factor XII to active factor XIIa.
 Factor XII is activated in vitro by exposing blood to
foreign surface (glass test tube).
 Activation in vivo occurs when blood is exposed to
collagen fibers underlying the endothelium in the
blood vessels.

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17. Clinical features
– Spontaneous bleeding from the nose, umbilicus,
brain, GIT or skin.
– The infant may have tar-colored stools, or
hematemesis
– Prolonged blood coagulation time.
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18. Diagnosis
• Hx of bleeding in the family
• Bleeding time
• PT(measures action of Prothrombine)
• PTT ( Measures activity of
Thromboplastine)
• INR (used to make sure the results from a
PT test is the same at one lab as it is at
another lab)
• INR = (Patient PT ÷ Control PT)
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19. Normal Ranges
• Normal values for people not on blood
thinners:
• PT: 10 to 12 seconds (this can vary
slightly from lab to lab)
• PTT: 30 to 45 seconds (this can value
slightly from lab to lab)
• INR: 1 to 2
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20. Management
– Treatment is with IV vitamin K.
– If bleeding is life-threatening
• fresh whole blood
– The infants should be observed for evidence of bleeding.
– Handling the infants carefully to avoid the slightest trauma and
possible blood loss
• Prevention
– Administration of vitamin K 1 mg stat at the time of birth
- Observe the new born of unusual bleeding from
skin cord & GI track (haematoemesis)
- Urine and stool are observed for blood (melanin -the
passage of black stool)
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