Jaundice < 24 Hours After Birth

Question 1

Over what percentage of newborn infants become visibly jaundice?

Answer 1

Over 50%

Question 2

Why do many newborns become jaundice?

Answer 2

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

Question 3

Why is neonatal jaundice important?

Answer 3

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

Question 4

What is kernicterus?

Answer 4

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

Question 5

When may kernicterus occur?

Answer 5

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

Question 6

Is free bilirubin fat soluble?

Answer 6

Yes - so it can cross the BBB

Question 7

The neurotoxic effects of bilirubin vary in severity from…

Answer 7

Transient disturbance to severe damage and death

Question 8

What are acute manifestations of kernicterus?

Answer 8

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

Question 9

Infants who survive kernicterus may develop…

Answer 9

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

Question 10

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

Answer 10

The introduction of prophylactic anti D immunoglobulin for rhesus negative mothers

Question 11

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

Answer 11

Slightly preterm infants (35-37 weeks)

Dark skin toned infants - jaundice more difficult to detect

Question 12

Babies become clinically jaundice when bilirubin level reach..

Answer 12

About 80 micromol/L

Question 13

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

Answer 13

Age of onset

Question 14

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

Answer 14

Haemolysis

Question 15

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

Answer 15

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

Question 16

What haemolytic disorders cause jaundice <24 hours after birth?

Answer 16

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

Question 17

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

Answer 17

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

Question 18

Is ABO more or less common than HDN?

Answer 18

More common

Question 19

How can ABO incompatibility cause jaundice ?

Answer 19

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

Question 20

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

Answer 20

True

Question 21

Where does G6PD deficiency have a high prevalence?

Answer 21

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

Question 22

What does G6PD prevent in red cells?

Answer 22

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

Question 23

G6PD deficiency is primarily seen in…

Answer 23

Males - it is x linked

Question 24

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

Answer 24

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

Question 25

How do children usually present with G6PD deficiency?

Answer 25

Neonatal jaundice - within first 3 days of life | Acute haemolysis - precipitated by infection, drugs

Question 26

How is spherocytosis inherited?

Answer 26

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

Question 27

What causes spherocytosis?

Answer 27

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

Question 28

How is spherocytosis diagnosed?

Answer 28

Spherocytes on blood film | Fragility tests/EMA binding

Question 29

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

Answer 29

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

Question 30

What is fetal hydrops?

Answer 30

Can occur in haemolytic disease of the newborn | Fluid accumulation in 2 or more compartments e.g ascites, pleural effusion, pericardial effusion, skin oedema

Question 31

Congenital infections are contracted when?

Answer 31

In utero /during delivery

Question 32

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

Answer 32

``` TORCH Toxoplasmosis Other - Hep B, syphilis, HIV Rubella Cytomegalovirus HSV ```

Question 33

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

Answer 33

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

Question 34

What is a transcutaneous bilirubinometer?

Answer 34

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

Question 35

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

Answer 35

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

Question 36

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

Answer 36

Total serum bilirubin | Record the time measurement was performed

Question 37

How do you test for rhesus haemolytic disease?

Answer 37

Direct Coombs test = positive

Question 38

Why is a family history of neonatal jaundice important?

Answer 38

Suggests there may be an underlying disease process present

Question 39

When is anti-D immunoglobulin administered?

Answer 39

During third trimester routinely if blood type is RhD negative

Question 40

The direct Coombs test is used to test for...

Answer 40

Autoimmune haemolytic anaemia

Question 41

Describe how the direct Coombes test is performed

Answer 41

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

Question 42

When is the indirect Coombs test done?

Answer 42

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

Question 43

Describe how the indirect Coombs test is performed

Answer 43

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