Prenatal Flashcards

1
Q

Diagnostic techniques (3)

A

Chorionic villus sampling Amniocentesis Cordocentesis (PUBS)

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2
Q

Chorionic villus sampling

A
  • can be performed transcervical or transabdominal
  • performed 11-13 weeks
  • problems: placental mosaicism (1-2%)
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3
Q

Amniocentesis

A
  • performed >15 weeks
  • can directly measure AFP and acetyl cholinesterase
  • Risk of miscarriage = 1/1000
  • Takes amniotic fluid; FISH results in 48 hours, Karyotype in ~2 weeks
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4
Q

Cordocentesis (percutaneous umbilical blood sampling - PUBS)

A
  • needle inserted into fetal umbilical cord
  • performed >18-20 weeks
  • diagnoses fetal blood: hematocrit, platelets, infection
  • therapeutic: transfusion, drugs
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5
Q

Screening techniques (5)

A
  • First Trimester Screening
  • Integrated/Sequential Screening
  • Second trimester multiple marker screening
  • Ultrasound
  • NIPT
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6
Q

First Trimester Screening

A
  • tests for Tri 18 and Tri 21
  • performed 11-14 weeks
  • NT measurement via u/s
  • hCG and PAPP-A measurement
  • risk adjustment
  • Tri 18; Tri 21 risk flagged if greater than 1/270
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7
Q

Quad Screening

A
  • Performed 16-22 weeks
  • blood test measuring hCG, AFP, eU3 and inhibin A
  • risk adjustment
  • Tri 18, Tri 21 and open NTD
  • Tri 21 risk flagged if greater than 1/270
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8
Q

NIPT

A
  • performed anytime after 10 weeks
  • blood test
  • detects Tri 13, Tri 18, Tri 21 and XY
  • can also detect Tri 16, Tri 22 and 7 microdeletions
  • can pick up placental mosaicism
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9
Q

Ultrasound

A
  • level 2 anatomy scan performed at 18-20 weeks
  • can detect open NTD, Tri 21, Tri 13 and Tri 18
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10
Q

Integrated/Sequential/Combined Screening

A

-combines first trimester screening and quad screening for more accurate results

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11
Q

High risk pregnancy (features/qualifications)

A
  • over 35 at delivery
  • abnormal FTS/maternal serum screen
  • abnormal ultrasound finding
  • personal/family history of aneuploidy
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12
Q

IDDM (Insulin-Dependent Diabetes Mellitus) marker levels

A
  • have lower MSAFP values than non-IDDM
  • higher incidence of open NTDs
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13
Q

African American marker levels

A
  • have a higher MSAFP concentration
  • lower incidence of open NTDs
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14
Q

Reasons for elevated MSAFP

A
  • underestimate gestational age
  • multiple pregnancy
  • open NTDs
  • abdominal wall defect
  • fetal and maternal blood mixed
  • unexplained
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15
Q

Indications to test Amniotic fluid AFP and Acetylcholinesterase

A
  • AFAFP >2.00 MoM
  • patient at increased risk for an open NTD based on family history
  • patient with IDDM
  • patient with elevated MSAFP
  • patient on valproic acid or tegretol
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16
Q

Down syndrome (marker pattern)

A
  • increased hCG
  • decreased AFP
  • decreased uE3
  • decreased PAPP-A
  • increased NT
17
Q

Trisomy 18 ultrasound findings

A
  • u/s detects ~80% of fetuses with Tri 18
  • IUGR
  • heart defect
  • strawberry shaped calvarium
  • clenched fist
  • rockerbottom feet
  • micrognathia
  • cleft lip +/- cleft palate
  • omphalocele (25% of cases)
  • diaphragmatic hernia
  • NTD
  • cystic hygroma
  • polyhydramnios
  • choroid plexus cysts
18
Q

choroid plexus cysts

A
  • cysts in the choroid plexus of the brain
  • finding in 1% of normal fetuses at 16-24 weeks
  • 90% resolve by 26-28 weeks
19
Q

Men over 45

A

-increased risk for new dominant mutations (cannot be tested for)

20
Q

Options for families with known conditions or abnormal test results (future pregnancies)

A
  • PGD
  • egg donation
  • sperm donation
  • adoption
21
Q

Risk of Down Syndrome with a carrier mother of a Robertsonian Translocation (13;21, 14;21, 15;21, or 21;22)

A

10 - 15 % risk of a baby with translocation Down syndrome

22
Q

Risk of Trisomy 13 with a carrier mother of a Robertsonian Translocation (13;14, 13;15, 13;21, or 13;22)

A

1% chance of having a baby with trisomy 13

23
Q

Risk of a chromosomal abnormality in baby of a carrier mother of a Robertsonian translocation (14;15, 14;22, or 15;22)

A

Almost certainly no risk of having a baby with a trisomy, but possible risk of miscarriage or UPD.

24
Q

Father with any Robertsonian translocation combination

A

Low risk, below 1%, of any child being affected

25
Q

Same-chromosome translocation (Robertsonian)

A
  • There is a group of carriers whose translocation chromosome consists of the two long arms of the same chromosome - 13;13, 14;14, 15;15, 21;21, or 22;22
  • These carriers will always produce eggs or sperm with unbalanced chromosomes - either with two copies of the chromosome or none
26
Q

What is the most common Robertsonian translocation?

A

13;14 (approximately 1 : 1,300 humans are a carrier)

(long arms of 13 and 14)

27
Q

1 in ____ people are Robertsonian carriers

A

1000

28
Q

What is an increased nuchal fold associated with?

A

Down Syndrome (Nuchal TRANSLUCENCY is associated with congenital heart defects as well, but nuchal FOLDS are not)