Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
31 Cards in this Set
- Front
- Back
|
What are amniocytes?
|
They are the cells in amniotic fluid, which come from different sources in the pregnancy.
|
|
|
When is the stardard amniocentesis done?
|
At 16 to 20 weeks of pregnancy (in 2nd trimester).
|
|
|
What is the most common indication for amniocentesis?
|
Advanced maternal age (35 yrs or great at time of delivery).
|
|
|
How long does it take to receive the results of chromosomal studies?
|
Approx 2 weeks
|
|
|
How long doe sit take to receive the results of DNA & metabolic studies?
|
May take longer than 2 weeks epending on the number of cells needed for analysis.
|
|
|
What are five complications of amniocentesis?
|
1. Spotting after the procedure.
2. Needle stick of the fetus. 3. Infection 4. Leakage of amniotic fluid. 5. Pregnancy loss |
|
|
What is the risk of pregnancy loss following amniocentesis?
|
0.5% (1 in 200)
|
|
|
How are amniocytes grown?
|
Directly on coverslips.
|
|
|
How accurate is amniocentesis for chromosomal problems?
|
Virtually 100% accurate.
|
|
|
How is chorionic villus sampling performed?
|
Via transcervical biopsy of chorionic villi using a flexible catheter and directed by ultrasonography.
|
|
|
How is amniocentesis performed?
|
Via transabdominal insertion of a needle under ultrasound guidance.
|
|
|
Can a transabdominal approach to chorionic villus sampling be performed?
|
Yes, using a spinal needle.
|
|
|
What are the two types of analyses used with chorionic villus sampling?
|
1. Direct analysis = analysis of chorionic ectoderm (results w/in 24 hrs).
2. Standard tissue culture = analysis of chorionic mesoderm (results in 2-4 weeks). |
|
|
When is chorionic villus sampling performed?
|
At 10-12 weeks gestation (first trimester)
|
|
|
Can we evaluate for neural tube defects using chorionic villus sampling?
|
No
|
|
|
What are the studies performed using amniocentesis?
|
1. Direct analysis of amniotic fluid for alpha-fetoprotein or acetylcholinesterases (risk factors for NTDs)
2. Karyotyping & Metabolic Studies 3. Cytogenetic studies 4. Enzyme analysis 5. Molecular analysis |
|
|
What studies are performed using CVS?
|
The same as amniocentesis except no alpha-fetoprotein or acetylcholinesterase analysis.
|
|
|
What are some problems/difficulties associated w/ chorionic villus sampling?
|
The chance for contamination by maternal cells is greatly increased over that for amniocentesis. Also, mosaicism is much more common.
|
|
|
What is confined placental mosaicism?
|
Mosaicism seen in the placenta but not in the fetus; likely seen in CVS because of the type of cells studied.
|
|
|
How accurate is chorionic villus sampling?
|
Because trophoblast analysis may not always reflect the genetic makeup of the fetus, it's not as accurate as the culturing of cells seen in amniocentesis.
|
|
|
How is fetal blood sampling performed?
|
A transabdominal needle is inserted under ultrasound guidance; it is penetrated near the insertion site into the placenta.
|
|
|
How can we confirm that origin of blood sample in FBS is actually from the fetus.
|
Measurement of MCV -- fetal RBCs are 120-160 fl, while adult RBCs are 80-95 fl.
|
|
|
When is FBS performed?
|
After 20 weeks gestation
|
|
|
What are the studies done in FBS?
|
The same except for the measurement of alpha-fetoprotein.
|
|
|
What is FBS generally useful for?
|
Detecting fetal infections and fetal anemia.
|
|
|
What is the risk of fetal loss after performing FBS?
|
Approx 1%
|
|
|
How accurate is FBS?
|
If fetal blood sample confirmed, FBS is very accurate.
|
|
|
What is preimplantation genetic diagnosis?
|
It is analysis of either the polar body or a blastomere removed from the 4-8 cell stage of blastocyst development.
|
|
|
Why is preimplantation genetic diagonis performed?
|
It was developed to be used in conjunction with IVF; it can determine whether an embryo is affected with a particular genetic disorder.
|
|
|
What is the main difficulty with preimplantation genetic diagnosis?
|
It is based on analysis of a single or very few cells.
|
|
|
When do fetal cells begin to cross the placenta?
|
In the first trimester.
|
