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Neonatal Medicine > Jaundice < 24 Hours After Birth > Flashcards

Jaundice < 24 Hours After Birth Flashcards

1
Q

Over what percentage of newborn infants become visibly jaundice?

A

Over 50%

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2
Q

Why do many newborns become jaundice?

A

There is marked physiological release of Hb from the breakdown of RBCs because of the high Hb concentration at birth
Red cell lifespan of new born infants is 70 days - markedly shorter than 120 for adults
Decreased bilirubin conjugation due to hepatic immaturity

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3
Q

Why is neonatal jaundice important?

A

May be sign of another disorder - haemolytic anaemia, infection, inborn error of metabolism, liver disease
Unconjugated bilirubin can be deposited in the brain esp basal ganglia and brainstem nuclei causing kernicterus

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4
Q

What is kernicterus?

A

Encephalopathy resulting from deposition of unconjugated bilirubin in basal ganglia and brainstem nuclei

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5
Q

When may kernicterus occur?

A

When the level of unconjugated bilirubin exceeds the albumin binding capacity of bilirubin in the blood

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6
Q

Is free bilirubin fat soluble?

A

Yes - so it can cross the BBB

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7
Q

The neurotoxic effects of bilirubin vary in severity from…

A

Transient disturbance to severe damage and death

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8
Q

What are acute manifestations of kernicterus?

A 
Lethargy 
Poor feeding 
In severe cases: 
Irritability
Increased muscle tone - arched back (opisthotonos)
Seizures 
Coma
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9
Q

Infants who survive kernicterus may develop…

A

Choreoathetoid cerebral palsy (due to damage to basal ganglia)
Learning difficulties
Sensorineural deafness

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10
Q

Kernicterus used to be an important cause of brain damage in infants with severe rhesus haemolytic disease but it has become rare since…

A

The introduction of prophylactic anti D immunoglobulin for rhesus negative mothers

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11
Q

A few cases of kernicterus continue to occur, especially in…

A

Slightly preterm infants (35-37 weeks)

Dark skin toned infants - jaundice more difficult to detect

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12
Q

Babies become clinically jaundice when bilirubin level reach..

A

About 80 micromol/L

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13
Q

What is a useful guide for the likely cause of jaundice?

A

Age of onset

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14
Q

Jaundice starting within 24 hours of birth usually results from what?

A

Haemolysis

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15
Q

Jaundice due to haemolysis is particularly important to identify because..

A

The bilirubin in unconjugated and can rise very rapidly and reach very high levels

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16
Q

What haemolytic disorders cause jaundice <24 hours after birth?

A

Rhesus haemolytic disease
ABO incompatibility
Glucose 6 phosphate dehydrogenase deficiency (G6PD)
Spherocytosis

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17
Q

The birth of an infant with severe HDN may present with..

A

Anaemia
Hydrops (accumulation of fluid in at least 2 foetal compartments)
Hepatosplenomegaly
Rapidly developing severe jaundice
But this is rare, affected infants usually identified antenatally and monitored and treated if necessary

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18
Q

Is ABO more or less common than HDN?

A

More common

19
Q

How can ABO incompatibility cause jaundice ?

A

Most ABO antibodies are IgM and do not cross the placenta, but some group O women have an IgG anti-A- haemolysin in their blood which can cross the placenta and haemolyse the red cells of group A infant. Occasionally group B infants are affected by anti-B haemolysins .

The haemolysis can cause severe jaundice, but not as severe as in rhesus disease.
Hb level usually normal or slightly reduced
Hepatosplenomegaly absent
The direct antibody test (Coombs test) = positive

20
Q

G6PD deficiency is the most common red cell enzymopathy. True or false?

A

True

21
Q

Where does G6PD deficiency have a high prevalence?

A

Individuals originating from central Africa, the Mediterranean, Middle and Far East
Different mutations of the gene have been described - leading to different clinical features in different populations

22
Q

What does G6PD prevent in red cells?

A

Prevents oxidative damage
It is the rate limiting enzyme in the pentose phosphate pathway
Red cells lacking G6PD are susceptible to oxidant induced haemolysis - usually caused by certain drugs

23
Q

G6PD deficiency is primarily seen in…

A

Males - it is x linked

24
Q

What drugs and chemical cause haemolysis in children with G6PD deficiency?

A

Antimalarials - quinine, primaquine, chloroquine
Antibiotics - sulphonamides, quinolones, nitrofurantoin
Analgesics - aspirin (high doses)
Chemicals - napthalene (moth balls) , divicine (fava beans - broad beans)

25
Q

How do children usually present with G6PD deficiency?

A

Neonatal jaundice - within first 3 days of life

Acute haemolysis - precipitated by infection, drugs

26
Q

How is spherocytosis inherited?

A

Usually autosomal dominant but in 25% there is no FH and is caused by new mutation
Main cause of haemolysis in north European children

27
Q

What causes spherocytosis?

A

Mutation in genes for proteins of the red cell membrane - spectrin, ankyrin or band 3
The red cell looses part of its membrane when it passes through the spleen - causes cell to become spheroidal (less deformable) and leads to their destruction in the microvasculature of the spleen

28
Q

How is spherocytosis diagnosed?

A

Spherocytes on blood film

Fragility tests/EMA binding

29
Q

Jaundice at birth can also be from congenital infection. In this case, is the bilirubin conjugated?

A

Yes

Infant has other abnormal clinical signs e.g growth restrictions, hepatosplenomegaly, thrombocytopenic purpura

30
Q

What is fetal hydrops?

A

Can occur in haemolytic disease of the newborn

Fluid accumulation in 2 or more compartments e.g ascites, pleural effusion, pericardial effusion, skin oedema

31
Q

Congenital infections are contracted when?

A

In utero /during delivery

32
Q

Congenital infections are grouped due to their shared clinical signs. What are they?

A 
TORCH 
Toxoplasmosis
Other - Hep B, syphilis, HIV
Rubella
Cytomegalovirus 
HSV
33
Q

When an infant presents with….you should think of congenital infections

A 
One or more of..
Microcephaly
Intracranial calcifications
Rash
Intrauterine growth restrictions 
Jaundice
Hepatosplenomegaly 
Elevated transaminase concentrations 
Thrombocytopenia
34
Q

What is a transcutaneous bilirubinometer?

A

A non invasive tool that uses light to measure the levels of bilirubin in blood

35
Q

A transcutaneous bilirubinometer used first line in the majority of neonatal jaundice presentations except…

A

Early neonatal jaundice < 24 hours
Gestational age <35 weeks
If encephalopathy suspected

36
Q

In early neonatal jaundice, what is the first line investigation?

A

Total serum bilirubin

Record the time measurement was performed

37
Q

How do you test for rhesus haemolytic disease?

A

Direct Coombs test = positive

38
Q

Why is a family history of neonatal jaundice important?

A

Suggests there may be an underlying disease process present

39
Q

When is anti-D immunoglobulin administered?

A

During third trimester routinely if blood type is RhD negative

40
Q

The direct Coombs test is used to test for…

A

Autoimmune haemolytic anaemia

41
Q

Describe how the direct Coombes test is performed

A

A blood sample taken
The RBCs are washed and then incubated with anti human globulin (Coombs reagent)
If the red cells agglutinate = positive

Suggests that the anti human antibodies are forming links between RBCS by binding to the antibodies on the RBCs

42
Q

When is the indirect Coombs test done?

A

Used in prenatal testing for pregnant women and in testing prior to a blood transfusion - the test detects antibodies against foreign RBCs

43
Q

Describe how the indirect Coombs test is performed

A

Recipients serum is obtained containing IgG
Donor’s blood sample is added to the tube with the serum
Recipient’s IgG’s that target the donor’s RBCs form antibody-antigen complexes
Anti-human IgG (Coombs antibodies) are added to the solution
Positive test= agglutination of RBCs - Coombs antibodies connect the antibody-antigen complexes together

Neonatal Medicine (12 decks)

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