Prenatal Diagnosis Flashcards
1
Q
goals of prenatal diagnosis
A
- provide info to parents about testing options
- detect anaomalies/disorders
- counsel/support
- fetal therapy if available
2
Q
noninvasive screens
A
- maternal serum
- sequencing of cell-free DNA in maternal plasma
- prenatal ultrasound
- fetal MRI
3
Q
Invasive Diagnostics
A
- chorionic villus smapling CVS
- amniocentesis
- cordocentesis
- fetal biopsy
- pre-implantation genetic diagnosis PGD
4
Q
first trimester tests/screens
A
- ultrasound
- NIPT
- NT, serum screen
- CVS
5
Q
second trimester test
A
- 2nd serum
- amniocentesis
- fetal anomaly scan
6
Q
tests arent done after second trimester…
A
because a decision of whether the baby is to be kept or not needs to happen within a certain time frame (legally)
7
Q
first screening question
A
how old are you?
8
Q
indications for invasive prenatal diagnosis
A
- maternal age 35 or older at time of delivery
- major anomoly on ultrasound
- abnormal maternal serum
- positive cell free DNA
- fmaily history of single gene disorder/chromosomal
- maternal anxiety
9
Q
screening for fetal down syndrome
A
- measure placental proteins
- nunchal translucency screening
- offer invasive test
10
Q
nuchal translucency
A
- normal fluid filled space between back of fetal neck and overlying skin
- increased in fetuses with: down syndrome, turner syndrome, trisomy 18, trisomy 13, triploidy
11
Q
maternal serum screening
-what must be known
A
- measurement of proteins produced by the fetus or placenta
- calculated relative to population standards
- mom and gest age must be known as well as race, diabetes, and smoking
12
Q
benefits of CVS
- cells are what so you can do what
- preferable to…
- does not detect…
A
- done at 11 weeks, restoring privacy to reproductive decision
- mitotically active cells = rapid karyotype
- tissue obtained is preferable for DNA analysis
- mosaic trisomy detected identifying fetuses risk for uniparental disomy
- does not detect mosaicism in the fetus itself
13
Q
risk of cVS
A
- elevated risk of fetal loss
- slightly elevated risk of maternal infection
- limb malformation syndrome
- confined placental mosaicism in 1% of cases
- amniotic fluid alpha fetoprotein not assayed (not info on neural tube defects
14
Q
amniocentesis
- cell arise from
- timeline
- associated birth defects
- type of analysis used
- risk
- mosaicism
A
- cells from amniotic fluid arise from fetal mouth and urniary bladder and amnios
- prefered at 15-17 weeks
- early amniocentesis associated with fetal club foot
- FISH analysis of non-dividing cells permits rapid diagnosis of aneuploidy
- risk of miscarriage 1/200 to1/600
- mosaicism in placenta not detected
15
Q
fetal cell-free DNA
- found where
- origin
- used for
A
- surprisingly high amounts of fetal DNA circulate in the blood of pregnant women
- origin of fetal DNA is in the placenta
- in 2011 started to be used as an advanced screen for fetal aneuploidy: trisomy 13, 18, 21; screening for sex chromosome anomalies, providing info on fetal sex