Home > Flashcards > Print Preview
The flashcards below were created by user
on FreezingBlue Flashcards. What would you like to do?
Give 3 reasons why newborns become visibly jaundiced?
- Increased breakdown of Hb as high conc at birth
- Their RBC lifespan is shorter (70d)
- Hepatic bilirubin METABOLISM is less efficient in the first few days of life
Why is neonatal jaundice important?
- Could be sign of other disease eg infection, haemolytic anaemia
What is kernicterus? Cause?
- Due to deposition of unconjugated bilirubin in BASAL GANGLIA and BRAINSTEM NUCLEI
When does kernicterus occur?
- When level of unconjugated bilirubin EXCEEDS ALBUMIN binding capacity of bilirubin of the blood
- As the free bilirubin is FAT SOLUBLE – it can cross BBB
What are the neurotoxic effects in kernicterus?
- Vary from transient disturbance
- Severe damage
What are acute manifestations of kernicterus?
Lethargy and poor feeding
What are symptoms/signs of severe kernicterus
- Increased muscle tone – cause baby to lie with ARCHED BACK = OPISTHOTONUS
What are the 3 consequences of infants who survive severe kernicterus?
- Choreoathetoid cerebral palsy – due to basal ganglia damage
- Learning difficulties
- Sensorineural deafness
What has reduced the incidence of kernicterus due to rhesus haemolytic disease?
Prophylactic anti-D immunoglobulin for Rh –ve mothers
What levels of bilirubin need to be reached for babies to become clinically jaundiced?
How do you classify the causes of neonatal jaundice?
- Age at onset
- <24h of age
- 24h – 3 weeks
- > 3 weeks
What are the 3 main large categories of jaundice < 24h age?
- Haemolytic disorders
- Congenital infection
Is jaundice in the 1st 24 hours of life physiological or pathological?
What are the 5 causes of haemolytic disorders that cause jaundice <24h age?
- 1. Rhesus haemolytic disease of the newborn
- 2. ABO incompatibility
- 3. G6PD deficiency
- 4. Hereditary spherocytosis
- 5. Pyruvate kinase deficiency
If rhesus haemolytic disease has not been identified antenatally, how could a severely affected infant be born?
- Severe jaundice, rapidly developing
Which other blood groups apart from Rhesus antigens could antibodies be formed to?
What cause of haemolytic disease is now more common than rhesus?
What type of Ig are most ABO antibodies? And can these cross placenta?
- These do not cross placenta
Which blood group in the mother can cause haemolysis in baby, why? What blood group is the baby usually?
- Group O women
- Some have IgG anti-A-haemolysin in the blood which can cross the placenta and haemolyse the RBC of a group A infant
- Occasionally group B infants are affected by anti-B haemolysins
What is the haemolysis in ABO incompatibility like compared to Rhesus?
- Less severe
- No hepatosplenomegaly
- Hb normal or slightly reduced
Which test is positive in ABO incompability?
- Direct Antibody Test = Coombs test
- Demonstrates antibody on surface of RBC
When does the jaundice in ABO incompatibility usually peak?
First 12-72 hours
What is the most common cause of severe neonatal jaundice worldwide needed exchange transfusion?
Which populations are more affected by G6PD deficiency?
- Middle east
What is the cause of G6PD deficiency?
What happens in G6PD deficiency?
- RBC do not generate enough glutathione to protect the cell from oxidant agents
- So break down
If G6PD deficiency a disease of males or females?
- Males more severely affected
- But females can manifest the phenotype
What are the main precipitants for acute haemolysis in G6PD deficiency?
- Fava beans - divicine
- Mothballs – naphthalene
What is the most common precipitating factor in G6PD deficiency?
Which drugs can cause haemolysis in G6PD deficiency?
- Antimalarials: chloroquine, primaquine, quinine
- Antibiotics: sulphonamides, quinolone
- Analgesic : aspirin high dose
Which foods need to be avoided in G6PD deficiency?
Fava beans (broad beans)
Is the haemolysis in G6PD deficiency intravascular or extravascular?
What other symptoms is acute haemolysis in G6PD deficiency assoc with?
- Dark urine – due to Hb and urobilinogen
How is the diagnosis of G6PD deficiency made?
- Measure G6PD activity in RBC
- Note during acute haemolytic crisis, G6PD levels might be misleadingly high due to higher enzyme conc in reticulocytes – which are made in increased numbers in response to haemolysis
- So a repeat assay is needed in the ‘steady state’ to confirm diagnosis
What is the mainstay of management of G6PD deficiency?
- Give parents advice about SIGNS of acute haemolysis: jaundice, pallor, dark urine
- List of drugs, chemicals, food to avoid
What is the inheritance of spherocytosis?
What is the defect in spherocytosis? And how does this lead to haemolysis?
- Abnormality in SPECTRIN – a major supporting component in RBC membrane
- RBC shape becomes spheroidal and less deformable leads to destruction in microvasculature in SPLEEN (extravascular haemolysis)
What are the clinical features of spherocytosis?
- Mild anaemia
- Jaundice, hyperbilirubinaemia
What are the 2 main complications of spherocytosis?
- Aplastic crisis 2ry to parvovirus B19 infection
- Gallstones due to increased bilirubin excretion
How is the diagnosis of spherocytosis confirmed?
- Osmotic fragility test: in hypotonic solutions spherocytes rupture more easily than biconcave RBC as they have maximal SA:vol ratio
- Also see spherocytes on peripheral blood film
What is Rx of spherocytosis?
- Folic acid to meet increased demands of marrow
- Splenectomy if severe (remember post splenectomy care…Pneumo, Meningo, Hib vaccine, pen proph)
What type of bilirubin does haemolysis produce?
Unconjugated (not water soluble, fat soluble so can cross BBB)
What type of bilirubin do you get from jaundice due to congenital infection?
Conjugated (water soluble as bound to glucuronic acid)
What is the most common cause of jaundice at 2 days to 3 weeks of age?
- Physiological jaundice – adapting to transition from fetal life
- Only use this term after other causes have been considered
- (due to liver enzyme immaturity and increased load of bili from RBC breakdown)
When does physiological jaundice usually peak?
How does feeding affect jaundice?
Jaundice is more common in breast fed babies
What type of hyperbilirubinaemia do you get with breast fed babies?
What is thought to be the cause of breast milk jaundice?
Increased enterohepatic circulation of bilirubin
What can exacerbate breast milk jaundice?
- Delay in establishing breast feeding – so inadequate bowel movements to remove bilirubin from body
- – then get dehydrated. May need iv fluids to correct it
- What is the advice in breast milk jaundice?
- Breast feeding should be continued
How long can breast milk jaundice continue up to?
Which infections can jaundice 2days – 2 weeks?
What other features can exacerbate a neonate’s jaundice?
- Polycythaemia hct>0.65
Which rare syndrome can cause very high levels of unconjugated bilirubin?
- Crigler-Najjar syndrome
- Enzyme glucuronyl transferase is deficient or absent
What is the definition of prolonged jaundice in a term baby?
> 14 days
What is the definition of prolonged jaundice in a preterm baby?
> 21 days
What are the causes of PROLONGED UNCONJUGATED hyperbilirubinaemia?
- Breast milk jaundice: most common, disappears 4-5weeks
- Infection – UTI
- Congenital hypothyroidism – may get prolojnged jaundice before symptoms of hypothyroidism occur (coarse facies, dry skin, hypotonia, constipation). Should be identified on neonatal screening – Guthrie test
- (also excess haemolysis: G6PD deficiency, ABO incompatibility)
How can you tell from mother’s history that it is CONJUGATED hyperbilirubinaemia?
- Pale stools
- Dark urine
- Poor weight gain
How do you tell on blood test that it is CONJUGATED?
>15% of total bilirubin is conjugated
What are the 2 main causes of prolonged neonatal jaundice with CONJUGATED hyperbilirubinaemia?
- Biliary atresia
- Neonatal hepatitis syndrome
Why is it important to diagnose biliary atresia promptly?
As delay in surgical Rx can adversely affect outcome
How is the severity of neonatal jaundice assessed?
- 1. Clinical assessment – blanch skin to assess jaundice (may underestimate in dark skin), check for hepatosplenomegaly (means it is not physiological jaundice)
- 2. Bilirubin level – transcutaneous or blood. Must have plasma level in significantly jaundiced baby. Plot serial measurements on chart – to see rate of change and anticipate need for treatment before rises to dangerous level (chart is gestation specific)
What is the definition of physiological jaundice (4 points)
- Onset after 24 hours of birth
- Resolves within 2 weeks
- More than 85% UNCONJUGATED
- Total bilirubin <350
How does gestation affect management of neonatal jaundice? Why?
- Lower treatment threshold if preterm
- As have lower albumin levels – so higher bilirubin levels (higher risk kernicterus)
Which risk factors for jaundice need to be asked about?
- Haemolysis: antenatal antibodies
- Check if mother is group O blood
- Origin- Mediterranean, Far Eastern or Afro-Caribbean (G6PD deficiency)
- Sepsis, unwell, acidosis, low serum albumin
How do you check the need for treatment in jaundice?
- Plot bilirubin on chart relating bilirubin with age
- Plot rate of change of bilirubin
- Allow for gestation, age and RF
What are the 2 main forms of Rx for jaundice?
- Phototherapy – most widely used therapy
- Exchange transfusion – for severe cases
How does phototherapy work for jaundice?
- Blue light (not UV)
- Wavelength 450nm
- Converts bilirubin in the skin and superficial capillaries into harmless water soluble metabolites
- Which are excreted in urine and through bowel
What other ‘nursing’ techniques are used during phototherapy?
- Eyes covered to prevent discomfort
- Additional fluids given to counteract increased losses from skin
What are the 2 main forms of phototherapy?
- Over head light source
- Fibre optic blanket applied directly to skin
- Can use both for maximum phototherapy = double/intensive phototherapy
When is exchange transfusion required for jaundice Rx?
- If bilirubin rises to a potentially dangerous level
- Especially if there is anaemia from haemolysis
- Or low serum albumin
What are the advantages of exchange transfusion?
- Rapidly reduces level of circulating bilirubin
- In isoimmune haemolytic disease also removes circulating antibodies and corrects anaemia
What is the traditional method of transfusion?
Via Umbilical artery and vein catheters
How much blood is given during exchange transfusion?
- Twice the infants blood volume
- Ie 2 x 80ml/kg is exchanged over 2 hours