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OBG: Oncology and neonatalology > Neonatal jaundice > Flashcards

Neonatal jaundice Flashcards

1
Q

What defined clinically apparent jaundice?

A

serum bilirubin >75mmol/L

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2
Q

What proportion of newborns may suffer from clinically apparent jaundice?

A

more than half

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3
Q

What is the cause of most neonatal jaundice?

A

harmless physiological jaundice

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4
Q

What are 2 reasons that physiological jaundice frequently occurrs?

A
  1. Higher turnover of red cells in fetus and higher normal concentration of Hb
  2. Fetal liver doesn’t handle unconjugated bilirubin but leaves it to cross placenta to be conjugated by maternal liver + excreted. Neonatal liver can’t immediately handle all of unconjugated bilirubin
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5
Q

What happens to the liver in the first few day sof live?

A

liver function rapidly improves, but while this is happening serum unconjugated bilirubin invariably rises

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6
Q

What is the risk of raised unconjugated bilirubin?

A

it is lipid soluble so it can cross the blood-brain barrier and is toxic to the CNS - can lead to bilirubin encephalopathy (kernicterus)

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7
Q

Which 2 parts of the CNS in particular are at risk if unconjugated bilirubin crosses the BBB?

A
  1. Basal ganglia
  2. Auditory pathways
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8
Q

What are 3 possible implications of kernicterus?

A
  1. Athetoid cerebral palsy
  2. Deafness
  3. Can be lethal
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9
Q

What level of unconjugated serum bilirubin must usually be exceeded to injure the brain of a healthy term infant?

A

>500 mmol/L

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10
Q

Does kernicterus occur with physiological jaundice?

A

no

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11
Q

What are 3 groups of causes of pathological neonatal jaundice?

A
  1. Excessive production of bilirubin
    • intravascular haemolysis due to rhesus or ABO incompatibility or inherited red cell defects
    • bruising
    • polycythaemia
  2. Diminished conjugation
    • breast milk jaundice
    • hypothyroidism
    • hepatic enzyme deficiencies
    • inborn errors of metabolism
    • hepatitis from various causes
  3. Obstruction
    • atresia of intra- or etrahepatic bile ducts
    • congenital bile duct cyst
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12
Q

What are 3 causes of excessive production of bilirubin leading to pathological neonatal jaundice?

A
  1. Intravascular haemolysis due to rhesus or ABO incompatibility or inherited red cell defects (spherocytosis, G6PD deficiency)
  2. Bruising
  3. Polycythaemia
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13
Q

What are 5 pathological causes of neonatal jaundice due to diminished conjugation?

A
  1. breast milk jaundice
  2. hypothyroidism
  3. hepatic enzyme deficiencies
  4. inborn errors of metabolism
  5. hepatitis from various causes
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14
Q

What are 2 obstructive causes of pathological jaundice in the newborn?

A
  1. biliary atresia: intra- or extra-hepatic
  2. congenital bile duct cyst (choledochal cyst)
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15
Q

What are 5 indicators that neonatal jaundice may be pathological?

A
  1. Becomes apparent within first 24h
  2. Rises faster than 75mmol/L per day
  3. Exceeds 250 mmol/L
  4. Persists beyond 14 days
  5. Is associated with pale stools, dark urine or bilirubinuria
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16
Q

What are 6 important investigations for suspected pathological jaundice in the newborn?

A
  1. Mother’s blood group, baby’s blood group and Coombs test - to look for rhesus or ABO incompatibility
  2. Haemoglobin and blood film - to look for anaemia and signs of haemolysis
  3. Unconjugated and conjugated serum bilirubin concentrations (split bilirubin) - to estimate the risk of encephalopathy and look for signs of obstruction
  4. Liver function tests - for evidence of liver disease
  5. Test urine for reducing substances (? galactosaemia)
  6. Check thyroid screening result and repeat if indicated
17
Q

What is thought to cause breastmilk jaundice in the neonate?

A

Thought that compounds in the milk of some women interfere with conjugation of bilirubin in the baby’s liver

18
Q

Why is breast milk jaundice problematic?

A

harmless condiion but there’s no specific test for it

19
Q

How does breastmilk jaundice present?

A

persistent jaundice which is mainly unconjugated

20
Q

What are 2 things that must be excluded before a diagnosis of breast milk jaundice can be made?

A

hypothyroidism and hepatitis

21
Q

What is the presenation of obstructive jaundice?

A

jaundice persisting beyond 2 weeks; pale stools and dark urine, bilirubinuria

22
Q

What are 4 investigations that should be performed in suspected obstructive jaundice?

A
  1. Test urine for bilirubin
  2. Ultrasound to look at biliary tree
  3. Radioisotope scan of biliary tree
  4. Liver biopsy (possibly)
23
Q

What is the management of biliary atresia?

A

Kasai portoenterostomy: surgical anastomosis of liver to small bowel

24
Q

When does the success of Kasai portoenterostomy decrease considerably?

A

if performed after 8 weeks

25
Q

What will be required long term for many survivors biliary atresia after neonatal surgery?

A

liver transplantation

26
Q

What cause of pathological jaundice is most likely to cause encephalopathy (kernicterus)?

A

rhesus disease (also occasionally with ABO incompatibility, other haemolytic disorders)

27
Q

What treatment means that rhesus disease causing haemolytic jaundice is rare now?

A

anti-D immunoglobulin to treat rhesus negative women after childbirth or obstetric procedures

28
Q

When does ABO incompatibility usually exist?

A

group O mother having group B or A baby

29
Q

What are the 2 forms of treatment for pathological jaundice?

A
  1. Phototherapy
  2. Exchange transfusion
30
Q

What does phototherapy involve?

A

high-intenity light in 450nm wavelength to convert stable lipid-soluble unconjugated bilirubin into unstable water-soluble isomers which can be excreted in the bile without need for conjugation

31
Q

How long does it take for phototherapy to have an effect on the rate of rise of bilirubin?

A

12-24h

32
Q

What determines whether phototherapy or exchange transfusion is used to treat pathological jaundice?

A

depending on whether certain threshold crossed for each specific to age - higher threshold for exchange transfusion

OBG: Oncology and neonatalology (14 decks)

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