Perinatal medicine Flashcards
what are the possible causes of jaundice soon after birth?
ABO/rhesus incompatibility
Infection
G6PD deficiency
spherocytosis
–> all of these cause haemolysis
a newborn has meconium ileus. what do you want to screen for?
cystic fibrosis
what are some features on examination/observation that may indicate that a preterm baby’s true gestational age?
Feet- less creases on the soles, may be entirely smooth if very preterm
Ears- look at the level of development of the pinna in preterm babies
Genitalia- clitoris more prominent in female preterm babies with smaller labia majora, absent rugae in scrotum and undescended testes
Skin- darker skin generally than term babies
Neuro: overall less tone- more floppy, extended position rather than flexed
Behaviour: weaker cry, poor suckling reflex (only really develops around 34 weeks)
what does the agpar score refer to? what are its components?
evaluates the CNS status and general adaptation of the newborn to the extrauterine environment
looks at HR, RR, colour, reflex irritability, muscle tone 1 minute and 5 minutes post delivery
give each a score from 0-2 for each parameter
0 being most abnormal, 2 being normal so i.e. full marks= normal baby
how might we elicit reflex irritability in a newborn?
firm stroking the soles of the feet–> irritability demonstrated with vigorous cry
why might a neonate be jaundiced physiologically?
hepatic processing system for bilirubin not efficient in first few days of life
neonatal hb has a shorter lifespan than than adults- approx 70 days vs 120 days in adults
there is a generally high Hb level at birth and this leads to high breakdown products–> clinical jaundice
what bilirubin level leads to clinically apparent jaundice in a neonate?
80 micromols/l and above
tell me the mechanism of phototherapy used to manage neonatal jaundice.
450nm wavelength of light causes photoisomerisation and photo-oxidation of bilirubin in the skin–>
changes the structural conformation of unconjugated bilirubin–> watersoluble–>
can be excreted without conjugation into the urine
what is the risk of leaving high levels unconjugated haemoglobin in a jaundiced infant?
risk of kernicterus- encephalopathy due to deposition of unconjugated bilirubin in the brain
what is meconium ileus?
impacted meconium in distal ileum
what is hirshsprung’s disease and what is the typical presentation in a newborn?
hirshsprung’s disease= incomplete development of the enteric nervous system in the large bowel.
neonates present with delayed passing of meconium (more than 2 days post birth) and signs of bowel obstruction
how sensitive is the heel prick test for CF in a newborn?
95% sensitive
an newborn infant is found to have excessive drooling at birth. what must we consider and investigate for?
oesophageal atresia (missing middle segment of oesophagus), commonly associated with distal tracheoesophageal fistula
a pregnant mother (gestation prior to 20 weeks) comes to see you because she noticed that one of her children has ‘slapped cheeks’. She is worried about parvovirus B19 infection. What would you do and tell her?
Most pregnant women (60%) are seropositive, meaning they are immune. Often the child is infectious prior to the appearance of slapped cheeks.
Perform serology looking for parvovirus IgM. If seronegative, perform serology again in 2 weeks. if seroconversion noted, then she has 50% chance the fetus will be infected–> requires serial u/s post this if seroconversion noted
what is the main outcome of confirmed parvovirus infection in a pregnant woman?
if less than 20 weeks gestation, there is a 50% chance of fetal loss or hydrops foetalis
no congenital abnormalities known to be associated with parvovirus
what are the two types of neonatal sepsis and how are they defined?
EOS= early onset sepsis (within a week post birth)
LOS= late onset sepsis (presents later than 7 days post birth)
what are the three main bacterial pathogens which cause neonatal sepsis?
streptoccus agalactiae (group B strep) -most common
listeria monocytogenes
e.coli- becoming increasingly common
how might we antenatally screen for risk of GBS neonatal sepsis?
at 35-37 gestation week vaginal swabs for GBS. if the pregnant woman is colonised with GBS, prophylactic antibiotics are used
if a pregnant woman is a known carrier of GBS, or have had previous pregnancies where GBS has been detected, no screening required and go straight to prophylactic antibiotics
other than cause sepsis in a neonate, what other conditions can GBS cause?
pneumonia
meningitis
an antenatal u/s scan in 3rd trimester demonstrates bilateral hydronephrosis and a full bladder in a male infant. what does this indicate?
posterior urethral valves
baby will be put on prophylactic trimethoprim post birth and be referred for surgery.
what is the most important step in neonatal resuscitation
Ventilation
NOT chest compression or medications
describe fetal blood flow circulation
vast majority of fatal blood from right side of the head goes through the PDA –> left ventricle (bypasses the lung)
only 10% CO go into the lungs
Most of CO goes into the lower limbs
Describe the changes in cardiorespiratory system post birth in a newborn?
Lung expands, peripheral vascular resistance decreases, systemic vascular resistance goes up –> pulmonary blood flow increases–> functional closure of ductus arterosus
what are some ways that we can assess fetal wellbeing?
Hx:
• Fetal movements?
Ex:
• Fundal height measured in cm; absolute and serial measurements
Ix:
Ultrasound and cardiotocography (CTG)
what does ‘wet lung’ mean in obstetrics?
transient tachypnoea of the newborn due to fetal lung fluid
how might we prevent meconium aspiration syndrome in utero?
prevent post-maturity
prevent asphyxia
a newborn exhibits respiratory distress. other than pulmonary disorders, what are some other things you should consider?
- sepsis
- hypothermia
- hypoglycaemia
- anaemia
- CHD
what is bronchopulmonary dysplasia?
chronic lung disease acquired from long term ventilation post delivery
when is phototherapy indicated for neonatal jaundice?
Phototherapy is only indicated if there is too much unconjugated bilirubin
a neonate appears greenish yellow and has pale stools for a prolonged period of time. what must you consider?
Green-tinge jaundice, pale stools= conjugated hyperbilirubinaemia/obstructive jaundice
–> must consider biliary atresia
what must you do to delineate the cause of prolonged jaundice in a neonate i.e. > 10 days? what are your ddx for prolonged jaundice?
Prolonged jaundice: measure levels of conjugated vs unconjugated bilirubin
Unconjugated causes= breastmilk jaundice, UTI, galactosaemia, hypothyroidism + SEPTICAEMIA!
Conjugated causes= BILIARY ATRESIA
what must you do when you notice the baby is jaundiced before 24 hrs post birth?
Need to do a DAT (direct Coombs antibody test) and check the maternal and newborn’s blood group + blood film
–> this is haemolytic disease of the newborn
when does physiological jaundice peak post birth in a neonate?
day 3 post birth
