Neonatal jaundice Flashcards
(18 cards)
What is jaundice?
- Abnormally high levels of bilirubin in the blood
- RBCs contain unconjugated bilirubin so when they break down, the release this bilirubin into the blood
- Unconjugated bilirubin is conjugated in the liver
- Conjugated bilirubin is excreted with via the biliary system into the GI tract or via the urine
What is physiological jaundice?
- high conc of RBCs in the foetus and neonate
- These RBCs are more fragile than normal RBCs
- Fetus and neonates have less developed liver function
- Fetal RBCs break down more rapidly than normal red blood cells → release lots of bilirubin
- This bilirubin is normally excreted via the placenta but at birth the baby no longer has access to the placenta to excrete bilirubin
- This then leads to a normal rise in bilirubin shortly after birth → yellow skin and sclera from 2-7 days after age
What are the causes of jaundice from increased production of bilirubin?
Haemolytic disease of the newborn, ABO incompatibility, haemorrhage, intraventricular haemorrhage, cephalo-haematoma, polycythaemia, sepsis, DIC, and G6PD deficiency.
What are the causes due to decreased clearance of bilirubin?
- prematurity
- Breast milk jaundice
- Neonatal cholestasis
- Extrahepatic biliary atresia
- Endocrine disorders (hypothyroid and hypopituitary)
- Gilbert syndrome
What is there an increased risk of when premature neonates have jaundice?
In premature babies, the process of physiological jaundice is exaggerated due to the immature liver, increasing the risk of complications, especially kernicterus.
Why are babies who are breastfed more likely to have neonatal jaundice?
- components of breast milk inhibit the ability of the liver to process bilirubin
- Breastfed babies are more likely to become dehydrated if not feeding adequately
- Inadequate breastfeeding may lead to slow passage of stools, increasing the absorption of bilirubin in the intestines
What is haemolytic disease of the newborn?
- a cause of haemolysis and jaundice
- It’s caused by incompatibility between rhesus antigens on the surface of the RBCs of the mother and fetus (rhesus antigen on the rbc varies between individuals
What is the most important antigen in the rhesus blood system?
Rhesus D antigen.
What happens if a pregnant woman is rhesus D negative?
- chance that the baby will be rhesus D positive (has the rhesus D antigen)
- At some point the blood from the baby will enter the mother’s blood stream
- When this happens, the baby’s RBCs will display the rhesus D antigen
- The mothers immune system will recognise this rhesus D antigen as foreign and will produce antibodies against the rhesus D antigen
- The mother has then become sensitised to rhesus D antigens
What does this sensitization lead to?
Usually, this sensitization doesn’t cause problems during the first pregnancy. However, during subsequent pregnancies, the mother’s anti-D antibodies can cross the placenta into the fetus, leading to haemolysis, anaemia, and high bilirubin levels, resulting in haemolytic disease of the newborn.
When is jaundice considered as ‘prolonged’?
When it lasts longer than expected in physiological jaundice:
- >14 days in full-term babies
- >21 days in premature babies.
What are some conditions that can cause prolonged jaundice?
Biliary atresia, hypothyroidism, and G6PD deficiency.
What are the investigations for jaundice?
- FBC and blood film - look for polycythaemeia or anaemia
- Conjugated bilirubin - elevated levels indicates hepatobiliary cause
- Blood type testing of mother and baby for ABO or rhesus incompatibility
- Direct Coombs test for haemolysis
- Thyroid function esp hypothryoid
- Blood and urine culture of infected suspected
- G6PD levels
What is the management for jaundice?
A treatment threshold chart to monitor total bilirubin levels specific for the gestational age of the baby at birth. If the total bilirubin level reaches the threshold, treatment is initiated to lower bilirubin levels.
What is phototherapy?
- it converts unconjugated bilirubin into isomers that can be excreted in the bile and urine without needed conjugation in the liver
- Blue light shines on the baby’s skin and little to no UV light is used
- Double phototherapy involves 2 boxes
- Bilirubin is closely monitored during treatment
What is measured after phototherapy and when?
Rebound bilirubin is measured 12-18 hours after stopping to ensure the levels don’t rise above the threshold.
What is kernicterus?
Brain damage caused by excessive bilirubin levels. It is the main reason that neonatal jaundice is treated to keep bilirubin levels below certain thresholds.
How does kernicterus occur and how does it present?
- unconjugated bilirubin can cross the BBB
- Excessive bilirubin causes direct damage to the CNS - basal ganglia and brainstem
- Less responsive, floppy, drowsy baby with poor feeding
- The damage to the CNS is permanent ⇒ cerebral palsy, learning disability and deafness
