Neonatal jaundice and Rhesus disease Flashcards
What are some of the causes of neonatal jaundice?
Physiological
Blood group incompatibility (most commonly Rhesus or ABO incompatibility)
Other haemolytic disorders e.g. G6PD deficiency
Sepsis
Liver disease
Metabolic disorders
Why does physiological jaundice occur?
Increased production
Decreased uptake and binding by liver cells
Decreased conjugation (most important)
Decreased excretion
Increased enterohepatic circulation of bilirubin
What time frame (from birth) is jaundice always considered pathological?
<24 hours from birth
What is normally the cause of babies born with jaundice (or jaundice within first 24 hours)?
Haemolysis with excess bilirubin production
What are the common causes of haemolysis in the newborn?
ABO incompatibility
Rh immunisation
Sepsis
What measurement of bilirubin might indicate that a newborn has hepatitis?
Substantial levels of conjugated bilirubin (>15% of total)
What investigations should be done in early pathological jaundice?
Total and conjugated serum bilirubin concentration (SBR)
Maternal blood group and antibody titres (if Rh negative)
Baby’s blood group, direct antiglobulin (Coombs) test (detects antibodies on the baby’s red cells), and elution test to detect anti-A or anti-B antibodies on baby’s red cells
Full blood examination, looking for evidence of haemolysis, unusually-shaped red cells, or evidence of infection
CRP might assist with diagnosis of infection
Why might the serum bilirubin concentration be ‘too high’ in newborns aged 24hours - 10 days with jaundice?
- mild dehydration/insufficient milk supply (breast-feeding jaundice)
- haemolysis
- breakdown of extravasated blood (e.g. cephalhaematoma, bruising, CNS haemorrhage, swallowed blood)
- polycythaemia (increased RBC mass)
- infection
- increased enterohepatic circulation (e.g. gut obstruction)
When is jaundice in a newborn deemed to have gone on for ‘too long’?
>10 days, especially >2 weeks
What are the causes of persisent unconjugated hyperbilirubinaemia in the newborn?
- breast milk jaundice (diagnosis of exclusion, cessation not necessary)
- continued poor milk intake
- haemolysis
- infection (especially urinary tract infection
- hypothyroidism
What are the causes of persistent conjugated bilirubinaemia in the newborn?
Hepatitis
Biliary atresia
Why might a newborn have hepatitis?
Can be caused by infection (toxoplasmosis, rubella, cytomegalovirus, hepatitis, or syphilis), or by metabolic disorders (e.g., galactosaemia)
What is kernicterus?
The permanent consequences of bilirubin toxicity
What are the signs of acute bilirubin encephalopathy?
- lethargy
- poor feeding
- temperature instability
- hypotonia
- arching of the head, neck and back (opisthotonos)
- spasticity
- seizures
What factors increase the risk of kernicterus?
- increasing unconjugated bilirubin
- decreasing gestation: preterm infants may be at risk at lower concentrations of bilirubin, 300 micromol/L or less
- asphyxia, acidosis, hypoxia, hypothermia, meningitis, sepsis, and decreased albumin binding
How should neonatal jaundice be treated?
Treatment of cause e.g. infection, hypothyroidism
Adequate hydration from breast milk or formula
Phototherapy
Exchange transfusion
IV immunoglobulin (for haemolytic disease)
What factors would indicate jaundice in a newborn was likely physiological?
Onset day 2
Peak day five
Resolve by day 10-14
Otherwise well infant
What factors would indicate jaundice in a newborn was likely pathological?
Onset day 1
Peak: variable
Prolonged after day 14
Symptoms and signs of aetiological cause e.g. Pale stool
What is meant by rhesus -ve?
Lacking rhesus factor/anti-D antigens
In what scenario does Rhesus disease cause problems in pregnancy?
Pregnancies of a rhesus -ve mother, having a baby with a rhesus +ve partner, giving a rhesus +ve baby
During the first pregnancy, the mother may be come exposed and produce anti-D antibodies
This will affect subsequent pregnancies with rhesus +ve babies, which the mothers antibodies may try to attack if blood comes into contact
What complication in the newborn might rhesus disease cause?
Haemolytic disease of the newborn
What is Coombs test?
A prenatal test used in pregnant women to detect antibodies against red blood cells that may cause haemolytic disease of the newborn
In an affected rhesus +ve baby, what would happen to the following cord blood parameters:
- haemoglobin?
- bilirubin?
- Coombs test?
Haemoglobin - decreased
Bilirubin - increased
(both of these indicate haemolytic anaemia)
Coombs test positive
When can anti-D be given to prevent rhesus isoimmunisation following the event of feto-maternal transfusion?
28 to 30 weeks
Or within 72 hours of sensitisation
What is the ideal site and route of administration of anti-D?
IM deltoid tubercle
What is the dose of anti-D based on gestational age (in emergency)?
250 units <20 weeks
500 units >20 weeks
What is the prophylactic dose of anti-D?
1500 units during pregnancy
+ 500 after delivery
What three events in pregnancy would anti-D be administered?
Trauma
Amniocentesis
Ectopic pregnancy
Is administration of anti-D post-delivery indicated in this case?
Rh -ve mother
ABO compatible
Rh +ve baby
Coombs test -ve
Infant bilirubin level normal
Yes - this will prevent sensitisation and protect future pregnancies
Is administration of anti-D post-delivery indicated in this case?
Rh -ve mother
ABO incompatible
Rh -ve baby
Coombs test -ve
Infant bilirubin level normal
No - no point, no exposure to anti-D antigen
Is administration of anti-D post-delivery indicated in this case?
Rh -ve mother
ABO compatible
Rh +ve pregnancy
Coombs test +ve
Infant bilirubin level increased
No - too late, mother is already sensitised and baby has already been affected
Is administration of anti-D post-delivery indicated in this case?
Rh +ve mother
ABO incompatible
Rh -ve baby
Coombs test +ve
Infant bilirubin level increased
No - mother already sensitised
Coombs +ve because ABO incompatible
