Jaundice in a term infant

Question 1

How is bilirubin formed?

Answer 1

Conversion of haem to biliverdin then bilirubin

Question 2

What are the causes of neonatal jaundice?

Answer 2

Physiological
Blood group incompatibility (rhesus or ABO0
Haemolytic disorders (G6PD deficiency) 
Sepsis
Liver disease
Metabolic disorders

Question 3

Why does physiological jaundice develop?

Answer 3

Increased production
Decreased uptake and binding by liver cells
Decreased conjugation
Decreased excretion
Increased enterohepatic circulation of bilirubin

Question 4

What is important about jaundice before 24 hours of age?

Answer 4

ALWAYS pathological; usually due to haemolysis

Question 5

Why can babies be born with jaundice?

Answer 5

Haemolysis

Hepatitis

Question 6

What are the causes of haemolysis?

Answer 6

ABO incompatibility
Rh isoimmunization
Sepsis
Red cell enzyme defects (G6PD deficiency)

Question 7

What should be considered if there is substantial elevation of conjugated bilirubin in a baby born with jaundice?

Answer 7

Hepatitis

Question 8

How is early pathological jaundice investigated?

Answer 8

Total and conjugated serum bilirubin conc (SBR)
Maternal blood group and antibody titres
Baby blood group, direct agglutination (coombs)
FBC, smear
CRP

Question 9

What does a coombs test look for?

Answer 9

Detects antibodies on baby’s red cells

Not specific

Question 10

What can cause high bilirubin from 24 hrs - 10 days (not physiological)?

Answer 10

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)

Question 11

What causes persistent unconjugated hyperbilirubinaemia?

Answer 11

Breast milk jaundice (diagnosis of exclusion) 
Continued poor milk intake
Haemolysis
Infection (UTI)
Hypothyroidism

Question 12

Describe the jaundice assoc with hypothyroidism?

Answer 12

Persistent jaundice may be earliest sign

Treatment is vital to prevent profound developmental delay

Question 13

Describe the jaundice seen in haemolysis

Answer 13

Jaundice suddenly reappears after infant has gone home, severe haemolysis cause (G6PD deficiency)

Question 14

How is G6PD deficiency inherited?

Answer 14

X-linked

Question 15

What are the causes of persistent conjugated hyperbilirubinaemia?

Answer 15

Hepatitis (toxoplasmosis, rubella, CMV, hepatitis or syphilis) 
Biliary atresia (pale stools and dark urine)

Question 16

Can persistent conjugated hyperbilirubinaemia be normal?

Answer 16

ALWAYS pathological

Question 17

What can prolonged unconjugated bilirubin result in?

Answer 17

Crosses BBB leading to kernicterus; death of brain cells and yellow staining in grey matter

Question 18

What are the signs of acute bilirubin encephalopathy?

Answer 18

Lethargy
Poor feeding
Temp instability 
Hypotonia
Arching of head, neck and back 
Spasticity
Seizures

Question 19

What increases the risk of kernicterus?

Answer 19

Increasing unconjugated bilirubin >340 micromol/L
Decreased gestation
Asphyxia, acidosis, hypothermia, hypoxia, meningitis, sepsis, decreased albumin binding

Question 20

What is the treatment of persistent jaundice?

Answer 20

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

Question 21

How does phototherapy treat jaundice?

Answer 21

UV light isomerises (changes bonding) of bilirubin allowing it to be water soluble and excreted in urine

Question 22

How many babies will have visible jaundice in the first week of life?

Answer 22

60%

Question 23

What determines if jaundice is prolonged?

Answer 23

> 2 weeks in term

>3 weeks in preterm

Question 24

What is a likely physiological jaundice?

Answer 24

Onset day 2
Peak day 5
Resolve by day 10-14
Otherwise well

Question 25

What points to a likely pathological jaundice?

Answer 25

Onset day `1
Peak is variable
Prolonged after day 14
Sy and si of aetiological cause (pale stool)