Neonatal Jaundice Flashcards
Definition
- a yellow discolouration in a newborn baby’s skin and eyes
- occurs because the baby’s blood contains an excess of bilirubin
- Total serum bilirubin (SBR) >85umol/L
How many of all new-born infants become visibily jaundice
60%
Physiology of neonatal jaundice
- marked physiological release of haemoglobin from breakdown of red cells because of the high haemoglobin concentration at birth
- the red cell life span of newborns is 70days (adults 120 days)
- hepatic bilirubin metabolism is less efficent in the first few days
Why is neonatal jaundice important?
- It may be a sign of another disorder e.g. haemolytic anaemia, infection, metabolic disease
- Unconjugated bilirubin can be deposited in the brain, particularly in the basal ganglia, causing kernicterus
Definition of kernicterus
- Encephalopathy resulting from the deposition of unconjugated bilirubin in the basal ganglia and brainstem nuclei
- It occurs when the level of unconjugated bilirubin exceeds the albumin binding capacity of bilirubin in the blood
- As this free bilirubin is fat soluble, it can cross the BBB and cause effects
- The neurotoxic effects range from transient disturbance to severe damage and death
Assesment of the jaundice new-born
*
how does age of onset determine severity?
- If <24 hrs –> likely to be haemolysis and potentially serious
- if >2 weeks - persistent neonatal jaundice
<24hr causes:
- Rhesus incompatibility
- ABO incompatibility
- GP6D deficiency
If mothers blood group O (then ABO incompatibility), if mediterranean, far eastern or afro-carribean (G6PD) deficency
Rhesus incompatibility
- Condition that occurs during pregnancy if a woman has Rh- negative blood and her baby has Rh- positive blood.
- Patients body will react to the baby’s blood as a foreign substance.
- Body then creates antibodies against the baby’s Rh- positive blood.
- These antibodies don’t cause problems during a first pregnancy. This is because the baby is often born before many of the antibodies develop.
- During second pregnancy, Rh antibodies cross the placenta and attack the baby’s red blood cells. This can lead to haemolytic anaemia
ABO incompatibility
- More common that Rhesus as screened for antenatally.
- Maternal IgG antibodies with specificity for the ABO blood group system pass through the placenta to the fetal circulation where they cause haemolysis of fetal red blood cells which can lead to anaemia and HDN.
- Half of the cases occur in a firstborn and does not get more severe after further pregnancies
GP6D deficency
- Inherited condition in which the body doesn’t have enough of G^PD enzyme which helps red blood cells function normally.
- This can cause haemoluytic anaemia, usually after exposure to certain medications, foods, or even infections.
- Mainly in people originating in Mediterranean, middle east and far east. Mainly affects male infants
>24hr causes:
- Physiological jaundice
- breast milk jaundice
Physiological jaundice
Most babies who have jaundice during this period have no underlying cause and the bilirubin has risen as the infant is adapting to the transition from fetal life
Breast milk jaundice
More common and more prolonged in breast-fed infants. The hyperbilirubinaemia is unconjugated. The cause is multifactorial but may involve increased enterohepatic circulation of bilirubin
Investigations
- history and examination
- bloods - serum bilirubin
- FBC
- blood film
- blood group
- LFTs
- TFTs
- blood cultures- TORCH screen
- urine dipstick to look for bilirubin and a source of sepsis
- if prolonged then bilirary US
