Perinatal medicine

Question 1

what are the possible causes of jaundice soon after birth?

Answer 1

ABO/rhesus incompatibility
Infection
G6PD deficiency
spherocytosis

–> all of these cause haemolysis

Question 2

a newborn has meconium ileus. what do you want to screen for?

Answer 2

cystic fibrosis

Question 3

what are some features on examination/observation that may indicate that a preterm baby’s true gestational age?

Answer 3

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)

Question 4

what does the agpar score refer to? what are its components?

Answer 4

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

Question 5

how might we elicit reflex irritability in a newborn?

Answer 5

firm stroking the soles of the feet–> irritability demonstrated with vigorous cry

Question 6

why might a neonate be jaundiced physiologically?

Answer 6

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

Question 7

what bilirubin level leads to clinically apparent jaundice in a neonate?

Answer 7

80 micromols/l and above

Question 8

tell me the mechanism of phototherapy used to manage neonatal jaundice.

Answer 8

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

Question 9

what is the risk of leaving high levels unconjugated haemoglobin in a jaundiced infant?

Answer 9

risk of kernicterus- encephalopathy due to deposition of unconjugated bilirubin in the brain

Question 10

what is meconium ileus?

Answer 10

impacted meconium in distal ileum

Question 11

what is hirshsprung’s disease and what is the typical presentation in a newborn?

Answer 11

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

Question 12

how sensitive is the heel prick test for CF in a newborn?

Answer 12

95% sensitive

Question 13

an newborn infant is found to have excessive drooling at birth. what must we consider and investigate for?

Answer 13

oesophageal atresia (missing middle segment of oesophagus), commonly associated with distal tracheoesophageal fistula

Question 14

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?

Answer 14

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

Question 15

what is the main outcome of confirmed parvovirus infection in a pregnant woman?

Answer 15

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

Question 16

what are the two types of neonatal sepsis and how are they defined?

Answer 16

EOS= early onset sepsis (within a week post birth)

LOS= late onset sepsis (presents later than 7 days post birth)

Question 17

what are the three main bacterial pathogens which cause neonatal sepsis?

Answer 17

streptoccus agalactiae (group B strep) -most common

listeria monocytogenes

e.coli- becoming increasingly common

Question 18

how might we antenatally screen for risk of GBS neonatal sepsis?

Answer 18

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

Question 19

other than cause sepsis in a neonate, what other conditions can GBS cause?

Answer 19

pneumonia

meningitis

Question 20

an antenatal u/s scan in 3rd trimester demonstrates bilateral hydronephrosis and a full bladder in a male infant. what does this indicate?

Answer 20

posterior urethral valves

baby will be put on prophylactic trimethoprim post birth and be referred for surgery.

Question 21

what is the most important step in neonatal resuscitation

Answer 21

Ventilation

NOT chest compression or medications

Question 22

describe fetal blood flow circulation

Answer 22

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

Question 23

Describe the changes in cardiorespiratory system post birth in a newborn?

Answer 23

Lung expands, peripheral vascular resistance decreases, systemic vascular resistance goes up –> pulmonary blood flow increases–> functional closure of ductus arterosus

Question 24

what are some ways that we can assess fetal wellbeing?

Answer 24

Hx:
• Fetal movements?

Ex:
• Fundal height measured in cm; absolute and serial measurements

Ix:
Ultrasound and cardiotocography (CTG)

Question 25

what does ‘wet lung’ mean in obstetrics?

Answer 25

transient tachypnoea of the newborn due to fetal lung fluid

Question 26

how might we prevent meconium aspiration syndrome in utero?

Answer 26

prevent post-maturity

prevent asphyxia

Question 27

a newborn exhibits respiratory distress. other than pulmonary disorders, what are some other things you should consider?

Answer 27

1. sepsis
2. hypothermia
3. hypoglycaemia
4. anaemia
5. CHD

Question 28

what is bronchopulmonary dysplasia?

Answer 28

chronic lung disease acquired from long term ventilation post delivery

Question 29

when is phototherapy indicated for neonatal jaundice?

Answer 29

Phototherapy is only indicated if there is too much unconjugated bilirubin

Question 30

a neonate appears greenish yellow and has pale stools for a prolonged period of time. what must you consider?

Answer 30

Green-tinge jaundice, pale stools= conjugated hyperbilirubinaemia/obstructive jaundice

–> must consider biliary atresia

Question 31

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?

Answer 31

Prolonged jaundice: measure levels of conjugated vs unconjugated bilirubin

Unconjugated causes= breastmilk jaundice, UTI, galactosaemia, hypothyroidism + SEPTICAEMIA!

Conjugated causes= BILIARY ATRESIA

Question 32

what must you do when you notice the baby is jaundiced before 24 hrs post birth?

Answer 32

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

Question 33

when does physiological jaundice peak post birth in a neonate?

Answer 33

day 3 post birth