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MLSCI 263 > LECTURE - Maternal Serum Screening > Flashcards

LECTURE - Maternal Serum Screening Flashcards

1
Q

pregnancy complications on the maternal side

A
  • pre-existing disease = hypertension, autoimmune disease
  • ectopic pregnancy
  • gestational diabetes
  • gestational trophoblastic disease
  • mal-presentation at term
  • premature or post-term delivery
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2
Q

pregnancy complications - fetal

A
  • anomalies: chromosomal, teratogens, neural tube defects
  • amniotic fluid probs: oligohydramnios, polyhydramnios
  • hemolytic disease of the newborn
  • respiratory distress
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3
Q

pregnancy complications for both maternal and fetal

A

placental problems = preeclampsia, infection

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4
Q

screening to detect complications early

A
  • pre-pregnancy: identify infertility + women at risk + lifestyle education + counselling
  • early: confirmation of pregnancy + first-trimester prenatal screening + infection and BGs + Abs
  • mid: maternal serum prenatal screen, routine ultrasound (~5 months), gestational diabetes screen
  • late: prediction of pre-eclampsia
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5
Q

these induce birth defects by interfering with normal development

A

teratogens

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6
Q

list of teratogens

A
  • drugs of abuse
  • cigarettes
    = toxic metals, poorly controlled metabolic disorders
  • radiation
  • infections
  • meds (use min effective dose or alternative; anticonvulsant = phenytoin, valproate, anticoags like warfain)
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7
Q

how to confirm pregnancy

A
  • human chorionic gonadotropin (BhCG)
  • lateral flow immunoassays
  • urine = detectable 9-11 days after conception; 25-150 IU/L
  • plasma = 7-9 days; positive >5 IU/L (more sensitive!)
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8
Q

abnormal # of chromosomes

A

aneuploidy

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9
Q

T or F. all pregnant women have a small chance of having a pregnancy affected by a trisomy

A

T; prenatal screning provides an estimate of that chance

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10
Q

trisomy 21

A
  • Down syndrome
  • most common naturally occurring chromosomal rearrangement
  • 1/800 births
  • risk increases with maternal age; ge 40 = 1/100 chance of having live born baby with T21
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11
Q

organ effects of T21

A
  • brain: mental retardation. Alzheimer disease
  • heart: septal defects
  • GI: bowel atresia
  • blood: leukemia
  • reproductive: sterility in males
  • hypothyroidism, poor muscle tone, hearing + eye problems*
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12
Q

physical characteristics T21

A
  • flat facial profile, slanted eyes, short stature
  • Simian crease in palm
  • gap between toes
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13
Q

T18

A
  • Edwards syndrome
  • 1/7900 births
  • high frequency of fetal lost; most live a week or less
  • clinical features: dysmorphic, severe developmental delay, heart defects, facial clefts, spina bifida
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14
Q

T13

A
  • Patau syndorme
  • 1/9500 births
  • high frequency of fetal loss; miscarriage, stillbirth, or neonatal death; few survive to 6 mos
  • clinical features are severe: dysmorphic, growth retardation, cardiac, kdieny malformations, scalp defects, Omphalocele
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15
Q

Omphalocele

A

GI organs protrude through belly button in a sac

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16
Q

we need a high screen detection for prenatal screening

A

75% detection rate; no more than 3% false pos rate in first trimester and no more than 5% false pos rate in 2nd trimester

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17
Q

risk factors for aneuploidy

A
  • advancing maternal age >35 5y/o
  • previous affected pregnancy
  • parents who are carriers of a genetic translocation
18
Q

screening reports possible outcomes

A
  • screen negative: reduce risk
  • screen positive: increased risk; genetic counseling: non-invasive prenatal testing (NIPT), invasive prenatal testing
  • at least 5% false pos rate
    > 1 in 20 women will have a positive result
    > most will be false pos
19
Q

screening vs diagnostic tests

A
  • screening = results not definitive; give a risk, risk calc
    > 1st trimester combined screen and 2nd trim QUAD screen
    > asking woman her age; amniocentesis if 35 or older maybe?
    > cell free DNA
  • diagnostic = definitive results; karyotyping of fetal cell for aneuploidy (including T21, T18, T13)
    > obtained by CVS or amniocentesis
20
Q

malformations of baby due to congenital infections

A
  • Rubella
  • CMV
  • syphilis
  • chickenpox
21
Q

prenatal infections causing long-term disease in infant

A
  • HIV

- Hep B or C

22
Q

the condition of having an abnormal number of chromosomes

A

fetal aneuploidy
- can be chromosome number reduction (NOT a viable pregnancy) or increase
- often caused by faults in cell division of the gametes
> meiotic non-disjunction 95%

23
Q

neural tube defects

A

brain and/or spinal cord failed to develop properly
- during neuralation = neural tube does not close properly

classified as open or closed
- depends on type and thickness of membrane covering the neural tube defect

90% survival to at least age 30

24
Q

anencephaly

A

neural tube defect

- absence of brain; cranial vault (RARE but fatal)

25
Q

encephalocele

A

neural tube defect

brain protrudes through skull

26
Q

spina bifida

A

neural tube defect (spinal cord0

- more common than other two talked about

27
Q

first trimester combined screen

A
  • T21, 18, 13
  • Nuchal translucency + biochemical markers
    > requires ultrasound: gestational dating and NT
    > 11w2d to 13w6d
  • biochemical markers: bhCG and PAPP-A
    > bhCG = free beta human chorionic gonadotropin
    > PAPP-A = pregnancy associated plasma protein A (placenta)
28
Q

second trimester maternal serum QUAD screen

A
  • serum screen = biochemical markers only; 15w to 20w6d
  • AFP
  • hCG
  • DIA
  • uE3
29
Q

AFP

A

alpha-fetoprotein

  • synthesized by fetal liver
  • decreased in T18 an T21
30
Q

uE3

A

unconjugated estriol

  • steroid secreted by fetal liver and placenta
  • decreased in T18 and 21
31
Q

hCG in second trimester maternal serum screening

A
  • synthesized by trophoblastic cells
  • increased in T21
  • reduced in T18 and 13
32
Q

DIA

A

dimeric inhibin A

  • glycoprotein of unknown function
  • increased in T21
33
Q

when is 2nd trimester AFP only screen done?

A
  • pre-pregnancy BMI > or equal to 35 kg/m2
  • limited access to ultrasound

detection of open neural tube defects

elevated maternal serum AFP = requires U/S to check for other conditions

34
Q

ultrasound vs maternal serum AFP

A

AFP only = detect ONTDs

U/S = can detect both open and closed

35
Q

non-invasive prenatal screenings (NIPS)

A
  • done to decrease unnecessary invasive procedures (decrease false pos); enhance trisomy detection rate (decrease false neg)
  • for high risk pregnant women
    > advanced maternal age
    > positive maternal serum screen
    > previous pregnancy with chromosomal condition
    > abnormal U/S findings
36
Q

what is tested in NIPS and how?

A
  • materna blood plasma collected after 10 wks gestation
  • extracting free fetal DNa fragments to see if there really is problem with child’s genotype
    > quantitative counting or non-quantitative genotyping
    > targeted or untargeted (PCR, fluorescence, sequencing)

NOT COVERED

37
Q

tests available fo prenatal diagnosis

A
  • CVS = placenta (11-14 wks)
  • amniocentesis = amniotic fluid (14+ wks; preferably 16 wks)
  • gold standard tests = >99% specificity and sensitivity
  • BUT expensive, requires expertise, invasive (risk of fetal loss 1-2%), blood contamination
38
Q

only diagnostic test available in first trimester

A

chorionic villus sampling

39
Q

only diagnostic test available in the second or third trimesters of pregnancy

A

amniocentesis

40
Q

Diagnostic Tests (performed after amniocentesis and CVS)

A

Chromosome analysis
- rapid aneuploidy detection (RAD)
> detects aneuploidies on chromosomes 21, 18, 13, and X, Y
> quantitative fluorescent PCR on capillary sequencer

Ultrasound or Biochemical Measurement for NTD

  • amniotic fluid AFP (immunoassay)
  • CSF form of acetylcholinesterase (gel electrophoresis)

MLSCI 263 (31 decks)

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