Small For Dates Flashcards

1
Q

broadly speaking, what might cause a small baby?

A

pre term
small for gestational age (intra-uterine growth restriction(IUGR)/fetal growth restriction (FGR)
- constitutionally small

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2
Q

delivery before what week is considered term? what is mod-late, very and extreme pre-term?

A

before 37 weeks = pre term

  • mod-late preterm = 32-36+6 weeks
  • very preterm = 28-31+6 weeks
  • extreme pre-term = 24-27+6 weeks
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3
Q

baby born at what week has survival rate as full term?

A
34 weeks
(32 weeks = 95%)
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4
Q

what can cause pre-term labour?

A

infection
overdistention (multiple pregnancy, polyhydramnios)
vascular cause (placental abruption)
intercurrent illness (pyelonephritis/UTI, appendicitis, pneumonia)
cervical incompetence
40% are idiopathic

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5
Q

risk factors for preterm birth?

A
previous pre-term birth
multiple pregnancy
uterine anomaly
young age (teenagers)
parity
ethnicity
poor socio-economic status
smoking
drugs (esp cocaine)
low BMI
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6
Q

most common causes for preterm birth?

A

planned C/section (for severe pre-eclampsia, kidney disease or poor foetal development)
premature rupture of membrane
emergency event (placental abruption, infection, eclampsia etc)
40% unknown

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7
Q

definition of small for gestational age?

A

estimated fetal weight or abdominal circumference below 10th centile

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8
Q

what is defined as low birth weight?

A

birth weight <2.5kg (regardless of gestation)

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9
Q

what is IUGR/FGR defined as?

A

failure to achieve growth potential

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10
Q

symmetrical vs asymmetrical IUGR?

A

symmetrical (infection/chromosomal abnormality) = small head and small abdomen
asymmetrical (placental abnormality) = normal head, small abdomen

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11
Q

examples of risk factors for small for gestational age (SGA) pregnancy?

A
minor
- age >35 years
- IVF
- low BMI
- first pregnancy
- smoking
major
- age >40
- paternal SGA
- cocaine
- daily vigorous exercise
- chronic hypertension or complicated diabetes
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12
Q

how many major/minor risk factors warrant regular monitoring of growth?

A

1 major risk factor = regular US from 26-28 weeks until 36 weeks (serial growth scans)

3 minor risk factors = growth scan at 34 weeks
- if there was an abnormal uterine artery doppler at 20 weeks then they should be monitored as if they have 1 major risk factor

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13
Q

all women (regardless of risk factors) should have SFH measured from which week?

A

24 weeks
- growth scan if single measurement under 10th centile on customised chart or if serial measurements suggest slow/static growth

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14
Q

how is SGA diagnosed?

A

measurement of fetal AC
combine with head circumference +/- femur length to give EFW
can use additional information (liquor volume or amniotic fluid index and dopplers)

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15
Q

why are dopplers used in pregnancy?

A

provide information in the blood flow to baby through placenta
used at 20 weeks to scan uterine artery to look for a notch (showing resistance in vessel)
- resistance in uterine arteries can cause small baby

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16
Q

maternal factors in SGA?

A

lifestyle (smoking, alcohol, drugs)
height and weight
age
maternal disease (e.g hypertension)

17
Q

placental factors in SGA?

A

infarcts
abruption
often secondary to hypertension

18
Q

fetal factors in SGA?

A
infection (rubella, CMV, toxoplasma)
congenital abnormalities (e.g absent kidneys)
chromosomal abnormality (e.g Down's syndrome)
19
Q

possible consequences of IUGR?

A
antenatal/in labour = risk of hypoxia and/or death
post natal
- hypoglycaemia
- asphyxia
- hypothermia
- polycythaemia
- hyperbilirubinaemia
- abnormal reurodevelopment
20
Q

clinical features of poor growth?

A

predisposing factors present
fundal height less than expected
reduced liquor
reduced fetal movements (important symptom)

21
Q

how can fetal wellbeing be assessed?

A

assessment of growth
cardiotocography
biophysical assessment
doppler US (umbilical artery - measures resistance to flow)

22
Q

biophysical profile in pregnancy?

A
US (usually combined with CTG)
considers
- movement
- tone
- fetal breathing movements
- liquor volume

then scores out of 10

  • 8-10 = satisfactory
  • 4-6 = repeat
  • 0-2 = deliver fetus
23
Q

what do you want to see in umbilical artery doppler?

A
positive flow (even when mum is in diastole, baby is getting blood via placenta)
- wave pattern but never reaches zero

(bad if gaps seen and very bad if reversed - graph goes below zero in gaps)

24
Q

timing of delivery in SGA?

A

if all is well deliver by 37 weeks
indications for early delivery by C/section
- growth becomes static
- abnormal umbilical artery doppler
- normal umbilical artery doppler with abnormal MCA doppler between 32-37 weeks
- abnormal umbilical artery doppler with abnormal ductus venosus doppler between 24-32 weeks

25
Q

what is given if considering/planning early delivery

A
steroids (to help foetal lung maturity)
magnesium sulphate (gives some protection against cerebral palsy)