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Neonatology > Haematology > Flashcards

Haematology Flashcards

1
Q

What are the main causes of Neonatal Anaemia?

A
  • Physiological anaemia
  • Anaemia of Prematurity
  • Haemorrhage
    APH, twin -twin transfusion
  • Haemolysis
  • Hypoplasia/Aplasia eg. Blackfan Diamond
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3
Q

Symptoms of Neonatal Anaemia?

A

Hydrops Fetalis in severe disease

Pallor, tachycardia, respiratory distress, hepatosplenomegaly

Petechiae, purpura

Jaundice develops within first 24hrs

  • Amniotic fluid/umbilical cord may be bili stained
  • high risk of kernicterus
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4
Q

Describe Physiological Anaemia and the precipitating factors.

A

A physiological drop in Hb which happens in the 1st few weeks after birth - lowest around 3 months (Hb 90-100)

Factors causing the drop:
Temporary cessation of erythropoiesis
Reduced RBC survival time
Reduced production of erythropoietin

Exaggerated in preterm infants - occurs earlier and lasts longer.
Other factors - repeated blood sampling
- increased risk of iron deficiency

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5
Q

Common causes of Hydrops Fetalis?

A

Immune Hydrops:
RBC alloimmunisation diseases

Non-immune Hydrops:
Cardio abnormalities - heart failure
Arrythmias 
Chromosomal abnormalities 
Genetic/Metabolic abnormalities
Anaemia - thallasemias
Congenital (TORCH) infections
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6
Q

What can be done to prevent sensitisation in Rhesus -ve mothers?

A

ANTI-D GAMMAGLOBULIN for all non-immunised mothers

Routine administrations at 28weeks + within 72 hours of delivery
- Anti-D needed after sensitising events eg. Miscarriage, termination etc

Standard dose is 300micrograms - may need increased dose if large volume of blood transfused
- quantified by KLEIHAUER TEST

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7
Q

How do we identify a high risk pregnancy and how would they be managed antenatally?

A

Rhesus -ve mothers are screened for anti-D antibodies

Antibody titre >64 =significant haemolytic disease

  • Regular USS to monitor for Fetal Hydrops
  • Amniocentesis can assess haemolysis
  • PUBS (percutaneous umbilical blood sample)
    - Fetal Hb, allows transfusion in severe anaemia

Indications for delivery:

  • > 35 weeks gestation or pulmonary maturity
  • Fetal distress
  • Complications of PUBS
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8
Q

What would be the indication for a fetal transfusion antenatally?
And what blood products would be used?

A

Evidence of Hydrops Fetalis on USS or haematocrit < 30% on PUBS

CMV negative leukodepleted, irradiated RBC
- aiming Hct 45-55%

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10
Q

What are the indications for early and immediate Exchange Transfusion?

A

Immediate exchange transfusion:
- Hydrops Fetalis

Early exchange transfusion:

  • Cord bilirubin > 85
  • Cord Hb <100
  • Very high/rapidly rising SBR
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11
Q

ABO incompatibility is now the most common cause of heamolytic disease of the newborn.
What is the pathogenesis?

A

Anti-A or Anti-B antibodies are naturally occurring in A/B/O blood groups.

  • form mainly IgM (do not cross placenta)
  • small amounts of IgG produced
  • can occur in 1st pregnancy
  • more common in O blood group mothers

More mild than Rhesus disease as ABO has relatively low antigenicity (A1 >A2)

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12
Q

What are the clinical features of ABO incompatibility?

A

Jaundice within 24 hours
Anaemia uncommon
Hepatomegaly + Hydrops is RARE

DACT is weakly positive
Spherocytes on blood smear

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13
Q

Pathogenesis of Rhesus Disease?

A
  • Mother Rh negative, Fetus Rh positive
  • Maternal immune system sensitised by contact with Rh+ cells
  • Produces IgM then IgG against D antigen
  • Crosses placenta causing HAEMOLYSIS
  • Sensitisation caused by miscarriage, amniocentesis, terminations, delivery or Rhesus incompatible transfusions
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18
Q

Postnatal investigations in a neonate with Rhesus Disease?

A

Hb and Haematocrit
Platelets
Coombs test
Bilirubin

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19
Q

What is G6PD deficiency?

A

Glucose 6-phosphate dehydrogenase deficiency within RBCs causing increased susceptibility to haemolysis

X-linked recessive inheritance - MALES only
More common in Black African/Americans, Chinese populations

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20
Q

How does G6PD present?

A

Can cause spontaneous jaundice + anaemia.

More commonly precipitated by medications:

  • Anti-malarials
  • Nitrofurantoin/Sulfonamides
  • Chloramphenicol

Blood film - spherocytes, HEINZ BODIES
Reticulocytes

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21
Q

How do you diagnose polycythaemia in the neonate?

What are the common causes?

A

Free flowing blood sample with a Hct >65% or Hb > 220.

Common causes:
Chronic intrauterine hypoxia 
eg. SGA or post maturity
Delayed cord clamping, Twin- Twin transfusion
Infants of diabetic mothers
Neonatal Thyrotoxicosis 
Congenital Adrenal Hyperplasia
Beckwith-Wiedemann Syndrome
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22
Q

Many infants with polycythaemia are asymptomatic.

If symptoms do develop, how would they present?

A

Plethora, irritability, lethargy, tachyonoea
Raised SBR
Hypoglycaemia

Can present with signs of hyperviscosity:

  • Apnoeas
  • Tremors, seizures
  • Pulmonary Hypertension
  • NEC
23
Q

What is Haemorrhagic Disease of the Newborn and how does it present?

A

Vitamin K deficiency leading to a deficiency of the Vit K dependent clotting factors
- Factor 2, 7, 9 and 10

Neonates have an absence of gut flora which is involved in the production of Vit K.

Presents with spontaneous bleeding
- Can be early or late onset

24
Q

What are the common bleeding sites and the risk factors for early onset disease?

A 
Early onset is within 24 hrs of birth.
Common bleeding sites:       -Cephalohaematoma 
 - Subgaleal
 - Intracranial 
 - umbilical

Maternal medications main risk factor
Anticonvulsants eg. Phenytoin, phenobarb
Warfarin
Isoniazid

25
Q

Late onset disease tends to present at 1-6months and can cause more severe bleeding.
What are the characteristics of this late onset disease?

A

Common sites of bleeding:

  • Intra cranial
  • Gastrointestinal
  • ENT mucosa
  • Injection sites

Increased risk with :

  • Cholestasis eg. CF, biliary atresia, hepatitis
  • Exclusively breast fed infants
26
Q

What can cause Thrombocytopenia in the neonate?

A

Alloimmune thrombocytopenia

  • Similar pathogenesis to haemolytic disease, much rarer
  • usually transient fall in platelets
  • Can cause intra-cranial bleeds

Neonatal autoimmune ITP

  • In mothers with ITP
  • Maternal antibodies cross the placenta
  • High titres of maternal antibodies can indicate severity

Neonatology (1 decks)

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