Jaundice in a term infant Flashcards
How is bilirubin formed?
Conversion of haem to biliverdin then bilirubin
What are the causes of neonatal jaundice?
Physiological Blood group incompatibility (rhesus or ABO0 Haemolytic disorders (G6PD deficiency) Sepsis Liver disease Metabolic disorders
Why does physiological jaundice develop?
Increased production
Decreased uptake and binding by liver cells
Decreased conjugation
Decreased excretion
Increased enterohepatic circulation of bilirubin
What is important about jaundice before 24 hours of age?
ALWAYS pathological; usually due to haemolysis
Why can babies be born with jaundice?
Haemolysis
Hepatitis
What are the causes of haemolysis?
ABO incompatibility
Rh isoimmunization
Sepsis
Red cell enzyme defects (G6PD deficiency)
What should be considered if there is substantial elevation of conjugated bilirubin in a baby born with jaundice?
Hepatitis
How is early pathological jaundice investigated?
Total and conjugated serum bilirubin conc (SBR)
Maternal blood group and antibody titres
Baby blood group, direct agglutination (coombs)
FBC, smear
CRP
What does a coombs test look for?
Detects antibodies on baby’s red cells
Not specific
What can cause high bilirubin from 24 hrs - 10 days (not physiological)?
Mild dehydration/ insufficient milk supply (breast feeding jaundice)
Haemolysis
Breakdown of extravasated blood (cephalhaematoma, bruising, CNS haemorrhage)
Polycythaemia (increased RBC)
Infection
Increased enterohepatic circulation (gut obstruction)
What causes persistent unconjugated hyperbilirubinaemia?
Breast milk jaundice (diagnosis of exclusion) Continued poor milk intake Haemolysis Infection (UTI) Hypothyroidism
Describe the jaundice assoc with hypothyroidism?
Persistent jaundice may be earliest sign
Treatment is vital to prevent profound developmental delay
Describe the jaundice seen in haemolysis
Jaundice suddenly reappears after infant has gone home, severe haemolysis cause (G6PD deficiency)
How is G6PD deficiency inherited?
X-linked
What are the causes of persistent conjugated hyperbilirubinaemia?
Hepatitis (toxoplasmosis, rubella, CMV, hepatitis or syphilis) Biliary atresia (pale stools and dark urine)
Can persistent conjugated hyperbilirubinaemia be normal?
ALWAYS pathological
What can prolonged unconjugated bilirubin result in?
Crosses BBB leading to kernicterus; death of brain cells and yellow staining in grey matter
What are the signs of acute bilirubin encephalopathy?
Lethargy Poor feeding Temp instability Hypotonia Arching of head, neck and back Spasticity Seizures
What increases the risk of kernicterus?
Increasing unconjugated bilirubin >340 micromol/L
Decreased gestation
Asphyxia, acidosis, hypothermia, hypoxia, meningitis, sepsis, decreased albumin binding
What is the treatment of persistent jaundice?
Treat cause
Adequate hydration (breastfed; 8-12 times a day)
Phototherapy
Exchange transfusion
IV IgG if isoimmune haemolytic disease and rising bilirubin despite intensive phototherapy
How does phototherapy treat jaundice?
UV light isomerises (changes bonding) of bilirubin allowing it to be water soluble and excreted in urine
How many babies will have visible jaundice in the first week of life?
60%
What determines if jaundice is prolonged?
> 2 weeks in term
>3 weeks in preterm
What is a likely physiological jaundice?
Onset day 2
Peak day 5
Resolve by day 10-14
Otherwise well
What points to a likely pathological jaundice?
Onset day `1
Peak is variable
Prolonged after day 14
Sy and si of aetiological cause (pale stool)
