downs testing + pregnancy Flashcards

1
Q

naegele’s rule

A

predicts estimated due date based on onset of womens last menstrual period
add nine months to get due date - 280days

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2
Q

when is the site “rechecked” in placenta praevia?

A

at 32wks by US

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3
Q

initial antenatal screening for downs syndrome

A

all offered, indicates risk - NOT diagnostic
older mothers have higher risk

combined test
quadruple test

both return either a low or high chance result
- low -> 1 in 150 or more -> 1 in 300
- high ->1 in 150 ir less -> 1 in 100

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4
Q

combined test

A

first line
done between 11-13+6wks
involves combing results from
- nuchal translucency measurement - <3.5mm (normal when CRL is 45-84mm)
- serum beta-HCG
- PAPP-A

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5
Q

combined test results in Down’s vs Trisonmy 18(Edwards) + 13(patau)

A

downs
- increased HCG
- DECREASED PAPP-A
- thickened nuchal translucency (>6mm)

trisomy 18 (Edward) + 13 (patau)
- similar results but HCG tends to be lower

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6
Q

quadruple test for downs

A

if women book later in pregnancy - offered between 15-20wks
maternal blood tests -
- beta-HCG - higher indicates greater risk
- alpha-fetoprotein - lower
- unconjugated oestriol - lower
- inhibin A - higher

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7
Q

if “high risk” result in combined or quadruple test

A

offered:
- second screening test - NIPT
- diagnostic test - amniocentesis or chorionic villus sampling (CVS)

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8
Q

non-invasive prenatal screening test (NIPT)

A

v high sensitivity + specificity (>99%)
analysis small DNA fragment that circulate in blood of a pregnancy women (cffDNA)

  • cffDNA derives from placenta cells + is usually identical to fetal DNA - analysis allows detection of certain chromosomal abnormalities
  • cffDNA is detectable from around 10wks, amount rises as pregnancy continues
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9
Q

amniocentesis

A

involves US guided aspiration of amniotic fluid using a needle + syringe
- used later in pregnancy when there’s enough amniotic fluid to make it safer to take a sample
—> >15wks

miscarriage rate <1%

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10
Q

chorionic villus sampling (CVS)

A

involves US guided biopsy of placental tissue
- used when testing is done earlier**
—-> before 15wks

miscarriage rate <2%

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11
Q

booking visit

A

8-12weeks - ideally <10

  • info - diet, alcohol, smooking foic acid, vit D, take Hx
  • BP, urine dip, check BMI

bloods/urine
- FBC, blood group, rhesus status, red cell antibodies, haemoglobinopathies
- hep B, syphilis
- HIV offered to all
- urine culture to detect asymptoomatic bacteruria*

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12
Q

when is downs syndrome screening done?

A

11 - 13 +6wks

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13
Q

when is the anomaly scan done

A

18-20+6wks

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14
Q

what happens at 28wks of antenatal care

A

routine BP, urine dipstick, SFH

second screen for anaemia + atypical red cell alloantibodies

first dose of anti-D prophylaxis to rhesus neg women
(second given at 34wks)

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15
Q

how should fetal growth be monitored

A

serial measurement of symphysis fundal height (SFH) at each antenatal appointment from 24wks
- improve prediction of SGA neonate

plot on chart, lower than 10th centil measurement or serial static/slow growth -> refer for US

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16
Q

changes to pharmacokinetics in pregnancy

A

absorption affected by morning sickness
increased plasma volume + fat stores -> volume of distribution increases

decreased protein binding -> increased free drug

increased liver metabolism of some drugs -phenytoin

elimination of renally excreted drugs increases -> increase GFR

17
Q

changes to pharmacodynamics in pregnacy

A

no significant changes
pregnant women may be more sensitive to some drugs - hypotension with antihypertensives in 2nd trimester

18
Q

period of greatest teratogenic risk

A

4th-11th weeks

organogenesis
avoid all drugs if poss, unless benefit outweighs risk to foetus

19
Q

teratogenic drugs

A

ACEi/ARB -> renal hypoplasia
androgens
antiepileptics -> cardiac, facial, limb, neural tube defects
lithium - CVS defects
methotrexate ->skeletal defects
retinoids
warfarin * -> limb+facial defects

20
Q

seizures during pregnancy are assoc with what adverse effects

A

lower verbal IQ in child
hypoxia
bradycardia
antenatal death
maternal death

21
Q

why might seizures increase by 10% during pregnancy

A

non-complianse
changes to plasma conc of drugs
- persistent vomiting
- increased clearing

22
Q

in which trimester does blood pressure tend to drop

A

2nd trimester

23
Q

UTI in pregnancy Mx

A

nitrofurantoin

trimethoprim in 3rd trimester

24
Q

who should get VTE prophylaxis in pregnancy

A

2 or more risk factors
- obesity
- >35yrs
- smoker
- previous DVT
- Csection

at delivery + up to 7 days post partum

25
Q

VTE prophylaxis in pregnancy

A

LMWH

26
Q

problematic drugs in breatfeeding

A

o Phenobarbitone – actively concentrated in breast milk, suckling difficulties
o Amiodarone – neonatal hypothyroidism
o Cytotoxics – bone marrow suppression
o Benzodiazepines – drowsiness
o Bromocriptine – supresses lactation

27
Q

increasing calories during pregnancy

A

no need to in first 2 trimesters

last 12 weeks pregnant women requires 200 extra calories

28
Q

supplements during pregnancy

A

400mcg folic acid pre-conception + 1st trimester
10mg vit D through pregnancy + continuation if breast feeding

29
Q

consequences of folic acid deficiency

A

spina bifida
heart or limb defects
some childhood brain tumours
anaemia

30
Q

who gets a higher dose of folic acid (5mg)

A

previous pregnancy affected by spina bifida
women/partner has spina bifida
anticonvulsants for epilepsy
coeliac disease
diabetes
BMI 30 or more
sickle cell anaemia or thalassaemia - will also prevent + treat anaemia

folic acid deficiency

31
Q

whos at greatest risk of vit D deficiency

A

darker skin
indoors lots
clothes - muslim women
poor diet

32
Q

maternal + fetal risk of low vit D

A

maternal
- osteomalacia
- preeclampsia, gestational diabetes
- csection
- bacterial aginosis

fetal
- SGA
- neonatal hypocalcaemia
- asthmas/resp infections
- rickets