Jaundice < 24 Hours After Birth Flashcards
Over what percentage of newborn infants become visibly jaundice?
Over 50%
Why do many newborns become jaundice?
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
Why is neonatal jaundice important?
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
What is kernicterus?
Encephalopathy resulting from deposition of unconjugated bilirubin in basal ganglia and brainstem nuclei
When may kernicterus occur?
When the level of unconjugated bilirubin exceeds the albumin binding capacity of bilirubin in the blood
Is free bilirubin fat soluble?
Yes - so it can cross the BBB
The neurotoxic effects of bilirubin vary in severity from…
Transient disturbance to severe damage and death
What are acute manifestations of kernicterus?
Lethargy Poor feeding In severe cases: Irritability Increased muscle tone - arched back (opisthotonos) Seizures Coma
Infants who survive kernicterus may develop…
Choreoathetoid cerebral palsy (due to damage to basal ganglia)
Learning difficulties
Sensorineural deafness
Kernicterus used to be an important cause of brain damage in infants with severe rhesus haemolytic disease but it has become rare since…
The introduction of prophylactic anti D immunoglobulin for rhesus negative mothers
A few cases of kernicterus continue to occur, especially in…
Slightly preterm infants (35-37 weeks)
Dark skin toned infants - jaundice more difficult to detect
Babies become clinically jaundice when bilirubin level reach..
About 80 micromol/L
What is a useful guide for the likely cause of jaundice?
Age of onset
Jaundice starting within 24 hours of birth usually results from what?
Haemolysis
Jaundice due to haemolysis is particularly important to identify because..
The bilirubin in unconjugated and can rise very rapidly and reach very high levels
What haemolytic disorders cause jaundice <24 hours after birth?
Rhesus haemolytic disease
ABO incompatibility
Glucose 6 phosphate dehydrogenase deficiency (G6PD)
Spherocytosis
The birth of an infant with severe HDN may present with..
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
Is ABO more or less common than HDN?
More common
How can ABO incompatibility cause jaundice ?
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
G6PD deficiency is the most common red cell enzymopathy. True or false?
True
Where does G6PD deficiency have a high prevalence?
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
What does G6PD prevent in red cells?
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
G6PD deficiency is primarily seen in…
Males - it is x linked
What drugs and chemical cause haemolysis in children with G6PD deficiency?
Antimalarials - quinine, primaquine, chloroquine
Antibiotics - sulphonamides, quinolones, nitrofurantoin
Analgesics - aspirin (high doses)
Chemicals - napthalene (moth balls) , divicine (fava beans - broad beans)
How do children usually present with G6PD deficiency?
Neonatal jaundice - within first 3 days of life
Acute haemolysis - precipitated by infection, drugs
How is spherocytosis inherited?
Usually autosomal dominant but in 25% there is no FH and is caused by new mutation
Main cause of haemolysis in north European children
What causes spherocytosis?
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
How is spherocytosis diagnosed?
Spherocytes on blood film
Fragility tests/EMA binding
Jaundice at birth can also be from congenital infection. In this case, is the bilirubin conjugated?
Yes
Infant has other abnormal clinical signs e.g growth restrictions, hepatosplenomegaly, thrombocytopenic purpura
What is fetal hydrops?
Can occur in haemolytic disease of the newborn
Fluid accumulation in 2 or more compartments e.g ascites, pleural effusion, pericardial effusion, skin oedema
Congenital infections are contracted when?
In utero /during delivery
Congenital infections are grouped due to their shared clinical signs. What are they?
TORCH Toxoplasmosis Other - Hep B, syphilis, HIV Rubella Cytomegalovirus HSV
When an infant presents with….you should think of congenital infections
One or more of.. Microcephaly Intracranial calcifications Rash Intrauterine growth restrictions Jaundice Hepatosplenomegaly Elevated transaminase concentrations Thrombocytopenia
What is a transcutaneous bilirubinometer?
A non invasive tool that uses light to measure the levels of bilirubin in blood
A transcutaneous bilirubinometer used first line in the majority of neonatal jaundice presentations except…
Early neonatal jaundice < 24 hours
Gestational age <35 weeks
If encephalopathy suspected
In early neonatal jaundice, what is the first line investigation?
Total serum bilirubin
Record the time measurement was performed
How do you test for rhesus haemolytic disease?
Direct Coombs test = positive
Why is a family history of neonatal jaundice important?
Suggests there may be an underlying disease process present
When is anti-D immunoglobulin administered?
During third trimester routinely if blood type is RhD negative
The direct Coombs test is used to test for…
Autoimmune haemolytic anaemia
Describe how the direct Coombes test is performed
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
When is the indirect Coombs test done?
Used in prenatal testing for pregnant women and in testing prior to a blood transfusion - the test detects antibodies against foreign RBCs
Describe how the indirect Coombs test is performed
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
