Blood disorders Flashcards

1
Q

How does the haemostatic mechanism in newborns differ from that of older children?

A

In newborns, there is reduced activity of clotting factors, diminished platelet function, and suboptimal defense against clot formation.

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2
Q

causes of bleeding

A
  1. Deficiency of clotting factors / coagulopathy
  2. Platelet problems
  3. Vascular anomalies such as arterio-venous malformations and haemangiomas.
  4. Other
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3
Q

Deficiency of clotting factors / coagulopathy

A
  • Vitamin K deficiency / lack of administration (note: Vitamin K dependent
    factors II, VII, IX and X).
  • Maternal drugs (phenytoin, phenobarbitone, salicylates and warfarin).
  • Disseminated intravascular coagulopathy / DIC secondary to infection, shock,
    hypoxia, necrotising enterocolitis (NEC), renal vein thrombosis or use of
    venous catheters.
  • Inherited abnormalities (haemophilia, Turner syndrome, von Willebrand
    disease).
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4
Q

Platelet problems

A
  • Decreased production.
  • Increased destruction.
  • Dysfunction.
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5
Q

Other causes of bleeding

A
  • liver dysfunction.
  • trauma.
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6
Q

What aspects should be covered in the history when evaluating a bleeding newborn infant?

A

The history should include inquiries about familial bleeding disorders, maternal illness (such as infection and HELLP syndrome), and maternal drug use.

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7
Q

What should be assessed during the physical examination of a bleeding newborn infant?

A

During the physical examination, it is important to assess whether the infant appears sick or well, check for signs of shock, anemia, or dysmorphism, examine bleeding sites, and determine the presence of hepatosplenomegaly and jaundice.

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8
Q

What are the essential investigations needed for diagnosing a bleeding disorder in a newborn infant?

A

The essential investigations include a full blood count, blood smear examination, and coagulation profile (including INR, PT, and PTT). These tests help in evaluating various aspects of blood composition and coagulation function.

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9
Q

If the patient is sick what is the differential diagnosis

A

-DIC
-Platelet consumption (infection,
NEC, renal vein thrombosis)
-Altered vascular integrity
(extreme prematurity, hypoxia,
acidosis)
-Liver disease, heparinisation

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10
Q

If the patient is well what is the differential diagnosis

A

Immune thrombocytopaenia,
occult infection or thrombosis,
abnormal bone marrow function
-Vitamin K deficient bleeding of
the newborn
-Haemophilia
-Bleeding due to trauma,
anatomical abnormalities,
dysfunctional platelet disorders

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11
Q

DIC laboratory investigations

A

Platelets: low
INR (PT): high
aPTT: high

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12
Q

Platelet consumption laboratory investigations

A

Platelets: low
INR (PT): normal
aPTT: normal

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13
Q

Altered vascular integrity laboratory investigations

A

Platelets: normal
INR (PT): normal
aPTT: normal

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14
Q

Liver disease, heparinisation Laboratory investigations

A

Platelets: normal
INR (PT): high
aPTT: high

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15
Q

Immune thrombocytopaenia,
occult infection or thrombosis,
abnormal bone marrow function laboratory investigations

A

Platelets: low
INR (PT): normal
aPTT: normal

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16
Q

Vitamin K deficient bleeding of
the newborn laboratory investigations

A

Platelets: normal
INR (PT): high
aPTT: high

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17
Q

Haemophilia laboratory investigations

A

Platelets: normal
INR (PT): normal
aPTT: high

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18
Q

Bleeding due to trauma,
anatomical abnormalities,
dysfunctional platelet disorders laboratory investigations

A

Platelets: normal
INR (PT): normal
aPTT: normal

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19
Q

How is thrombocytopenia defined?

A

Thrombocytopenia is defined as a platelet count of less than 150 X 10^9/L. It is considered mild if 100 to 150 X 10^9/L, moderate if 50 to 99 X 10^9/L, or severe if less than 50 X 10^9/L.

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19
Q

causes of thrombocytopenia , early onset in a well infant

A
  • Fetal hypoxia.
  • Immune-mediated: autoimmune (mother has thrombocytopaenia / ITP or SLE) or
    alloimmune (mother has normal platelet count and there is passive transfer of
    maternal alloantibodies directed against paternally derived platelet antigens).
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20
Q

What are the classifications of thrombocytopenia based on timing and the infant’s condition?

A

Thrombocytopenia is classified as early (within 72 hours of life) or late (after 72 hours of life), and its etiology can be determined by assessing the infant as ill or well.

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21
Q

causes of thrombocytopenia , early onset in a sick or dysmorphic infant

A
  • DIC.
  • Congenital infection.
  • Genetic disorders or syndromes including (Trisomy 21, thrombocytopaeniaabsent-radii (TAR) syndrome, Wiskott-Aldrich syndrome and Fanconi anaemia)
  • Tumour (Kasabach-Meritt syndrome).
  • Thrombosis (renal vein).
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22
Q

Causes of thrombocytopenia , late onset

A

The most common cause is bacterial or fungal sepsis and NEC.
* Thromboses secondary to umbilical catheters.
* Drug-induced.
* Less common causes include inborn errors of metabolism and Fanconi anaemia.

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23
Q

What are the guidelines for platelet transfusion in newborn infants with thrombocytopenia?: If platelet count is less than 30 X 10^9/L

A

transfuse all newborn infants.

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24
Q

What are the guidelines for platelet transfusion in newborn infants with thrombocytopenia?: If platelet count is 30-49 X 10^9/L

A

transfuse if extreme low birth weight, less than one week of age, hypotensive requiring inotropic support, or with bleeding tendency (major or minor).

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25
Q

What are the guidelines for platelet transfusion in newborn infants with thrombocytopenia?: If platelet count is 50-99 X 10^9/L,

A

transfuse only if there is bleeding.

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26
Q

What are the guidelines for platelet transfusion in newborn infants with thrombocytopenia?: If platelet count is more than 99 X 10^9/L,

A

do not transfuse.

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27
Q

Why are newborn infants, especially preterm newborns, vulnerable to disseminated intravascular coagulopathy (DIC)?

A

Newborn infants, particularly preterm newborns, are vulnerable to DIC because anticoagulants such as antithrombin and protein C are normally low at this stage.

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28
Q

Main causes of DIC

A
  • Sepsis.
  • Perinatal hypoxia.
  • Respiratory distress syndrome.
  • Necrotising enterocolitis.
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29
Q

Clinical manifestations of DIC

A
  • Ill looking.
  • Petechiae.
  • Gastrointestinal haemorrhage
  • Oozing from puncture sites.
  • Signs of infection
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30
Q

investigations of DIC

A
  • Decreased platelet count.
  • Increased INR / PTT.
  • Fragmented red blood cells on blood smear.
  • Decreased fibrinogen.
  • Increased D-dimers.
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31
Q

What is the focus of management for disseminated intravascular coagulopathy (DIC)?

A

The focus of management for DIC is treating the underlying cause and ensuring that vitamin K has been given. Platelets, fresh frozen plasma, and cryoprecipitate should be considered as part of the treatment.

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32
Q

What is another name for vitamin K deficient bleeding of the newborn?

A

Vitamin K deficient bleeding of the newborn is also known as hemorrhagic disease of the newborn.

33
Q

Why is vitamin K essential for newborns?

A

Vitamin K is essential for the production of coagulation factors II, VII, IX, and X. Deficiency of vitamin K leads to inadequate activity of these factors, resulting in bleeding.

34
Q

Why do newborn infants have reduced vitamin K stores?

A

Newborn infants have reduced vitamin K stores due to poor placental transfer and deficient content in breast milk.

35
Q

How can the deficiency of vitamin K in newborns be classified?

A

The deficiency of vitamin K in newborns may be classified as early, classical, or late.

36
Q

early (within 24 hours) of vitamin k deficiency

A
  • Placental transfer of maternal drugs (anticonvulsants) inhibiting vitamin K
    activity.
37
Q

Classical (2nd to 7th day) of vitamin k deficiency

A
  • Inadequate supply of vitamin K in breastmilk
38
Q

Late (2nd to 12th week) of vitamin k deficiency

A
  • Malabsorption secondary to liver dysfunction.
  • Poor intake
39
Q

Clinical manifestations of vitamin K deficiency

A
  • Bleeding from the umbilicus.
  • Gastrointestinal bleeding.
  • Intracranial bleeding.
40
Q

Investigations of vitamin K deficiency

A
  • Normal platelet count.
  • Prolonged PT and PTT.
41
Q

What is the recommended prophylactic dose of vitamin K for all infants after delivery?

A

All infants should receive 1mg of intramuscular vitamin K as prophylaxis after delivery.

42
Q

What is the recommended course of action if bleeding occurs in newborns despite prophylactic vitamin K administration?

A

If bleeding occurs, a further vitamin K 1mg can be given intravenously, and fresh frozen plasma should be considered.

43
Q

Are oral supplements effective for preventing late-onset vitamin K deficiency bleeding in newborns?

A

Oral supplements for late-onset disease are shown to be less effective.

44
Q

What factors contribute to thrombosis in newborn infants?

A

Factors affecting blood flow, blood composition, and vascular endothelial integrity can all contribute to thrombus formation in newborn infants. Thrombosis occurs more frequently in the neonatal period than at any other age in childhood.

45
Q

What are the main risk factors or causes for thrombosis in newborn infants?

A

The main risk factors or causes for thrombosis in newborn infants include indwelling vascular catheters, polycythemia, and surgery. Inherited thrombophilias can occur but are rare.

46
Q

What is usually used as the first means of diagnosing thrombosis in newborn infants?

A

Doppler ultrasound is usually used as the first means of diagnosing thrombosis in newborn infants, while angiography is considered the gold standard.

47
Q

How are asymptomatic patients with thrombosis managed?

A

Asymptomatic patients are managed with close monitoring and supportive care.

48
Q

How are severe symptomatic cases of thrombosis treated in newborns?

A

Severe symptomatic cases of thrombosis in newborns are treated with anticoagulants and fibrinolytic agents. Surgical thrombectomy is rarely performed.

49
Q

What is the most common cause of anaemia in newborn infants?

A

The most common cause of anaemia in newborn infants is anaemia of prematurity, which is an exaggeration of a normal physiological anaemia. This typically occurs between 3 to 12 weeks of age and resolves by 3 to 6 months.

50
Q

Why does anaemia of prematurity occur in newborn infants?

A

Anaemia of prematurity occurs due to the transition from the fetal to neonatal environment, where oxygen saturation improves and erythropoietin levels drop markedly, leading to a decline in red blood cell production and haematocrit.

51
Q

What factors contribute to anaemia of prematurity in newborn infants?

A
  • Reduced red cell lifespan.
  • Rapid rate of growth of the preterm infant.
  • Frequent blood sampling.
  • Lower haemoglobin nadir as erythropoietin is produced by the preterm infant
    at Hb of 7 to 9 g/dL.
52
Q

What is the major site of erythropoietin production in the fetus?

A

In the fetus, the major site of erythropoietin production is the fetal liver.

53
Q

Other causes of anemia

A
  1. blood loss
  2. haemolysis
  3. In the fetus, the major site of erythropoietin production is the fetal liver.
54
Q

What are some obstetric causes of blood loss in newborn infants?

A

Obstetric causes of blood loss in newborn infants include abruption placentae, placenta previa, and rupture of the cord.

55
Q

What are some occult causes of blood loss in newborn infants?

A

Occult causes of blood loss in newborn infants include twin-to-twin transfusion, fetomaternal bleeding, and fetoplacental bleeding.

56
Q

What are some postnatal causes of blood loss in newborn infants?

A

Postnatal causes of blood loss in newborn infants include intracranial bleeding, massive cephalohematoma, ruptured liver or spleen, and bleeding from the umbilicus or gastrointestinal system.

57
Q

What are some iatrogenic causes of blood loss in newborn infants?

A

Iatrogenic causes of blood loss in newborn infants include blood sampling.

58
Q

Types of hemolysis

A

Immune haemolysis
Hereditary RBC disorders
Acquired haemolysis

59
Q

What are some causes of immune haemolysis in newborn infants?

A

Immune haemolysis in newborn infants can be caused by rhesus or ABO incompatibility, or minor blood group incompatibility.

60
Q

What are some examples of hereditary red blood cell disorders that can lead to haemolysis in newborn infants?

A

Hereditary red blood cell disorders that can lead to haemolysis in newborn infants include RBC membrane defects, metabolic defects, and haemoglobinopathies.

61
Q

What are some examples of acquired causes of haemolysis in newborn infants?

A

Acquired causes of haemolysis in newborn infants include infection, disseminated intravascular coagulation (DIC), vitamin E deficiency, and microangiopathic haemolytic anaemia.

62
Q

Diminished red blood cell production

A
  1. Diamond-Blackfan syndrome.
  2. Congenital leukaemia or other tumour.
  3. Infections.
  4. Drug-induced suppression of RBC production (eg. AZT).
63
Q

What aspects of family history should be explored when evaluating a newborn infant with suspected haemolysis?

A

Family history should include inquiries about anaemia, jaundice, gallstones, and splenectomy.

64
Q

How can acute blood loss manifest clinically in newborn infants?

A

Acute blood loss may result in shock, cyanosis, poor perfusion, and acidosis in newborn infants.

65
Q

What clinical features are associated with chronic blood loss in newborn infants?

A

Chronic blood loss in newborn infants is associated with pallor, mild distress, and irritability.

66
Q

What investigations are commonly performed to evaluate haemolysis in newborn infants?

A

Common investigations include
-blood smear for red blood cell morphology,
-reticulocyte count (high with chronic blood loss and haemolysis, low with infection and production defects), and
-Coombs test (positive in immune haemolysis such as blood group incompatibility).

67
Q

What is the purpose of the Apt test in newborn infants?

A

The Apt test is used to differentiate maternal from fetal blood. In a well infant when “gastrointestinal bleeding” is noted, this test can be done on gastric aspirates or stool to rule out the presence of swallowed maternal blood.

68
Q

How is the Apt test performed?

A

In the Apt test, 0.1 ml of sampled blood is added to a glass tube containing alkali and gently shaken for two minutes. The sample is considered contaminated with maternal blood if the color of the mixture changes from pink to brown. Fetal hemoglobin resists alkali denaturation and remains pink, while adult hemoglobin denatures and changes to brown.

69
Q

When is the Keihauer-Betke test considered in newborn infants?

A

The Keihauer-Betke test is considered if there is fetal demise or stillbirth, a sinusoidal fetal heart rate pattern, non-immune fetal hydrops, and severe neonatal anaemia.

70
Q

How is the Keihauer-Betke test performed?

A

In the Keihauer-Betke test, red blood cells from maternal circulation are fixed to a slide with an acidic solution. Adult red blood cells become ghost cells as hemoglobin A is soluble at this pH, while fetal hemoglobin remains pink as it is stable at low pHs.

71
Q

What is the primary focus of management for newborn infants with anaemia?

A

The primary focus of management is to determine and treat the underlying cause. Healthy asymptomatic newborn infants will self-correct mild anaemia if there are sufficient iron reserves.

72
Q

When are blood transfusions considered in newborn infants with anaemia?

A

Blood transfusions are considered in infants with symptomatic anaemia, significant respiratory disease, or congenital heart disease. Different thresholds for transfusions depend on chronological age, oxygen requirements, illness, or the need for surgery.

73
Q

How can iron supplementation benefit preterm infants?

A

Iron supplementation in preterm infants prevents late iron deficiency.

74
Q

What are the benefits of delayed cord clamping or cord milking after delivery of the infant?

A

Delayed cord clamping or cord milking after delivery of the infant has been shown to facilitate placental transfer, reducing the need for blood transfusions.

75
Q

What is the efficacy of erythropoietin in reducing the need for blood transfusions in newborn infants?

A

Erythropoietin has limited efficacy in reducing the number of blood transfusions and donor exposures. It may be a costly intervention and has been associated with an increased risk and severity of retinopathy of prematurity if given early.

76
Q

How is polycythemia defined in newborn infants?

A

Polycythemia is defined as a hematocrit more than 2 standard deviations above the normal value for gestational and postnatal age. In a term infant, polycythemia is defined as a hematocrit of more than 65% in a peripheral venous sample or hemoglobin more than 22 g/dL.

77
Q

What are some common symptoms of polycythemia in newborn infants?

A

Most infants with polycythemia are asymptomatic, but they may have features of thrombosis.

78
Q

How is polycythemia in newborn infants typically managed?

A

Most patients with polycythemia, whether symptomatic or asymptomatic, can be managed with intravenous hydration alone.

79
Q

What is a controversial treatment option for polycythemia in newborn infants?

A

Partial exchange transfusion is a controversial treatment option for polycythemia in newborn infants. It is associated with certain risks, such as necrotizing enterocolitis, and does not improve long-term neurodevelopmental outcomes.