Neonatal jaundice Flashcards
What is neonatal jaundice?
Jaundice - back up or build up of uncongugated bilirubin (fat soluble) causes discolouration i.e. problem with liver conjugation so system back up upstream or increased RBC breakdown
Jaundice is caused by the accumulation of bilirubin (bile pigment) produced from the breakdown of red blood cells.
60% of term neonates have physiological jaundice because bilirubin levels are higher than in adults due to neonates having a higher concentration of RBC with shorter life span.
Serum bilirubin >100micromol/L
What causes physiological jaundice?
When does it present, peak and start to decrease?
Physiological jaundice occurs in breastfed and formula-fed babies due to:
- Increased bilirubin production due to shorter RBC lifespan
- Decreased uptake by the liver
- Decreased conjugation in the liver due to hepatic immaturity
- Decreased excretion of bile pigment due to absence of gut flora
- Exclusive breastfeeding (esp. if feeding difficulty => reduced intake => dehydration => decreased bilirubin elimination => increased enterohepatic circulation of bilirubin.
Physiological jaundice appears ~2 days of age, peaks on days 3-5 and starts to decrease ~day 10.
*Physiological jaundice may co-exist with pathological jaundice.
What is breast milk jaundice?
What is the mechanism?
When does it present and peak?
Breast milk jaundice is a prolongation of physiological jaundice in breastfed babies.
=> Common in healthy, term, breastfed babies. Weight gain, stools, urine output and examinations are normal + neonate is well.
=> Mechanism is unknown but may be linked with decreased caloric intake and inhibition of hepatic bilirubin excretion
=> Infant not feeding well can lead to dehydration, malnutrition and high bilirubin levels increasing risk of bilirubin encephalopathy. Inadequate breastmilk intake = reduction in stool output, leading to resorption of bilirubin from the gut.
=> Usually presents ~day 2-4 and peaks on days 7-15. May persist up to 12 weeks
What causes pathological neonatal jaundice?
- Blood group incompatibility (commonly rhesus or ABO incompatibility)
- Other causes of haemolytic
- Sepsis
- Bruising
- Metabolic disorders e.g. galactoseamia, hereditary fructose intolerance, alpha-1 antitrypsin deficiency, hypothyroidism
- Gilbert’s syndrome (metabolic disorder - defective conjugating enzymes in liver => mild/intermittent elevation of unconjugated bilirubin)
Crigler-Najjar syndrome
- Glucose-6-phosphate-dehydrogenase deficiency (familial enzyme deficiency common in mediterranean, middle eastern, south east asian and african groups)
- Congenital obstruction & malformation of the biliary system i.e. biliary atresia => causes obstructive jaundice with conjugated hyperbilirubinaemia.
What is the prevalence of neonatal jaundice?
Jaundice is the most common requiring medical attention.
60% of term and 80% of pre-term babies develop jaundice in first week of life.
~10% of breastfed babies are still jaundiced at 1 month.
What are the risk factors for neonatal hyperbilirubinaemia?
- Decreased gestational age/preterm delivery
- Low infant birth weight
- Development of jaundice within first 24 hours of life
- Male
- Visible bruising
- Cephalhaematoma
- Maternal age > 25 years
- Maternal diabetes mellitus
- Asian, European or native American ethnicity
- Sibling born with jaundice requiring phototherapy / other treatment
- Dehydration
- Poor caloric intake / increased neonatal weight loss
- Breastfeeding
What are the complications of neonatal jaundice?
- Toxic to brain and spinal cord - unconjugated bilirubin can penetrate the blood-brain barrier.
The level at which bilirubin may cause neurotoxicity is dependent on prematurity, postnatal age, rate of serum bilirubin increase and co-existing illness i.e. sepsis, acidosis, hypoxia.
- Neurological consequences of hyperbilirubinaemia:
=> Acute bilirubin encephalopathy
=> Chronic bilirubin encephalopathy
=> Kernicterus
*Neurological complications in neonates with jaundice = rare
What is acute bilirubin encephalopathy?
Occurs when there is severe hyperbilirubinaemia.
Features include:
=> Lethargy
=> Irritability
=> Poor suck
=> Abnormal muscle tone & posture (opisthotonus)
=> High pitched cry
=> Apnoea
=> Seizures / coma (late signs)
What is chronic bilirubin encephalopathy?
Clinical features resulting from acute bilirubin encephalopathy.
Features include:
=> Athetoid cerebral palsy
=> Seizures
=> Developmental delay
=> Learning difficulties
=> Vision & hearing problems
=> Dental dysplasia
What is kernicterus (aka bilirubin encephalopathy)?
What are the acute symptoms?
What type of cerebral palsy can prolonged kernicterus lead to?
Kernicterus = term used to describe clinical features of acute / chronic bilirubin encephalopathy and pathological findings are deep yellow staining in the brain.
*Very high levels of unconjugated bilirubin (fat soluble) crosses the immature blood brain barrier.
Symptoms similar to acute / chronic bilirubin encephalopathy i.e. high pitched cry, seizures - can look similar to septic infection.
If prolonged, can lead to a permanent type of cerebral palsy known as choreoathetoid cerebral palsy and deadness.
What is the prognosis for neonatal jaundice?
Physiological jaundice is harmless and resolves by 2 weeks of age.
Breast milk jaundice in babies who are well is benign and self-limiting.
For most babies who require treatment for jaundice, phototherapy prevents bilirubin toxicity.
Secondary jaundice due to genetic / metabolic defects = prognosis variable
How is neonatal jaundice diagnosed?
Diagnosis is based on clinical observations esp within first 72 hours.
=> If the baby has >1 risk factors for hyperbilirubinaemia, ensure they are examined during first 48 hours.
=> Examine baby in bright, natural light and examine the skin on the whole body and blanch to assess for jaundice i.e. press on the nose.
=> If in doubt about diagnosis - refer to neonatologist or paediatrician
Important assessment in neonatal jaundice history
- Obstetrics history (inc mother’s rhesus status and blood group if known)
- Baby’s gestational age at birth
- Age of onset and duration of jaundice
- Feeding history (type of feeding and whether there have been problems with adequate intake)
- Number of wet / dirty nappies per day => helps assess hydration (specifically ask about presence of dark urine and or pale stool)
- Signs of illness i.e. lethargy, fever, vomiting, significant weight loss, irritability
- Family hx i.e.
=> significant haemolytic (inc. glucose-6-phosphate dehydrogenase deficiency)
=> Ask if siblings or close family have had hospital treatment for neonatal jaundice i.e. phototherapy or exchange blood transfusion
What are the causes of visible jaundice within 24h?
Visible jaundice within 24h is always abnormal
What investigations are carried out?
=> Sepsis
=> Rhesus haemolytic disease (+ve direct coombs test)
=> ABO incompatibility (mother O, baby A or B ; mother A, baby B or vice versa)
Direct coombs test +ve in 4%
Indirect coombs test +ve in 8%
Maternal IgG anti-A or anti-B is always present.
=> Red cell anomalies e.g. congenital spherocytosis (do fragility test / EMA binding), glucose-6-phophate dehydrogenase deficiency (do enzyme test)
Investigations: FBC, blood film, blood groups, coombs test
*Coombs test: detects antibodies that act against the surface of the red blood cells due to autoimmune haemolytic anaemia. +ve test = you have antibodies against your RBC
What are the causes of visible jaundice within 24h?
Visible jaundice within 24h is always abnormal
What investigations are carried out?
=> Sepsis
=> Rhesus haemolytic disease (+ve direct coombs test)
=> ABO incompatibility (mother O, baby A or B ; mother A, baby B or vice versa)
Direct coombs test +ve in 4%
Indirect coombs test +ve in 8%
Maternal IgG anti-A or anti-B is always present.
=> Red cell anomalies e.g. congenital spherocytosis (do fragility test / EMA binding), glucose-6-phophate dehydrogenase deficiency (do enzyme test)
Investigations: FBC, blood film, blood groups, coombs test
*Coombs test: detects antibodies that act against the surface of the red blood cells due to autoimmune haemolytic anaemia. +ve test = you have antibodies against your RBC
