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
