Week 2 Flashcards
What is chorionic villus sampling (CVS)?
Aspiration of a small amount of placental tissue (chorion) for chromosomal, metabolic, or DNA testing for fetal abnormalities caused by genetic disorders
when is chorionic villus sampling done?
Around 10-12 weeks gestation
how is chorionic villus sampling done?
Using a catheter either transvaginally through the cervix using an ultrasound guide or abdominally through a needle and ultrasonography
what are some advantages of chorionic villus sampling versus amniocentesis?
Can be performed earlier than amniocentesis but is not recommended before 10 weeks
examination of fetal chromosomes
what position would a woman be to do a chorionic villus sampling?
Lithotomy for transvaginal aspiration
supine for trans abdominal aspiration
how many times would you assess the fetal heart rate after a chorionic villus procedure?
Twice in 30 minutes post procedure
what is amniocentesis?
A needle is inserted through the maternal abdominal wall to gather amniotic fluid
when is amniocentesis commonly performed during pregnancy?
14 to 20 weeks gestation
what are some risk factors for fatal genetic disorders that might warrant amniocentesis?
Older than 35 years
history of genetic disorders
positive screening test such as alpha fetal protein
known or suspected hemolytic disease
what does amniocentesis test for?
Genetics, assessment of fetal lung maturity, and assessment of hemolytic disease, or interuterine infection
what are the advantages of amniocentesis?
Examines fetal chromosomes for genetic disorders
direct examination of biochemical specialists
accuracy rate of 99%
what might elevated bilirubin levels indicate on a amniocentesis?
Fetal hemolytic disease
positive PG indicates what on an amniocentesis?
Fetal lung maturity
L:S ratio >2:1 indicates what?
Fetal lung maturity
what are the risks of amniocentesis?
1% fetal loss rate after 15 weeks which increases to 2% to 5% earlier in gestation
Trauma to the fetus
Bleeding
Preterm labor
Maternal infection
RH sensitization from fetal blood to maternal circulation
what is delta OD 450?
Diagnostic evaluation of amniotic fluid obtained via amniocentesis product life threatening anemia in the fetus during the second or third trimester
what is an indication of delta OD 450?
When alloimmunzation exists from the increase risk for fetal anemia from RBC hemolysis
what is a safer alternative to delta OD 450for Rh alloimunized pregnancies?
Umbilical artery Doppler flow to measure the peak velocity of systolic blood flow in the middle cerebral artery of a fetus
what are some risks to Delta OD 450?
Membrane rupture
Infection
Worsening sensation
Fetal loss
what is alpha - fetoprotein?
Glycogen produced in the fetal liver, GI tract, and yolk sac in early gestation
what does AFP screen for?
Maternal blood screening for developmental defects in the fetus such as NTD and ventral abdominal wall defects
when is AFP screening done?
15-20 weeks
Increased levels of AFP are associated with what defects?
NTD, ventral abdominal wall defects
Decreased levels of AFP are associated with what defects?
Trisomy 21 also known as Down syndrome