Advanced Prenatal Eval Flashcards
benefits of ultrasound
noninvasive imaging of intrauterine contents
primary use of ultrasound
identify gestational age diagnose intrauterine pregnancy number of pregnancies (fetuses) assess for malformations and abnormalities (can be a sign of genetic disorders) fetal wellbeing
what is the degree of error for ultrasound identifying gestational age?
weeks equal to trimester it’s used
- 1st trimester = +/- 1wk, 3T = +/- 3wks
when is an ultrasound routinely performed
first trimester
second trimester - anatomy scan 18-22wks
labor and delivery - confirm cephalic lie or when BPP indicated
what is the umbilical artery doppler used for
monitoring growth-restricted babies
what is normal for umbilical arteries?
in normal babies, there’s high end diastolic flow in the umbilical arteries
what happens if resistance in the placenta increases?
end diastolic flow slows down and can be absent or reversed if severe
- indicative of an increased risk of mortality
- systolic/diastolic ratio is measured (increased is abnormal)
what is the MCA doppler used for?
assess for fetal anemia
what is seen on an MCA doppler
after 20wks, an increased flow by intracranial doppler is indicative of fetal anemia
when is an MCA doppler used
patients at risk for developing a fetal anemia, especially in the setting of alloimmunization
what is amniocentesis used for?
genetic diagnosis
when can amniocentesis be done?
as early as 15-20wks
what is amniocentesis
fluid taken from amniotic sac
when is amniocentesis reliable?
15wks
what are the risks of amniocentesis
pregnancy loss
what do you look at for amniocentesis
amniocytes
when is chorionic villous sampling (CVS) used?
high risk or desire diagnosis early
- advanced maternal age (>35)
- those who have suffered from infants with birth defects, fetal demise, and intellectual disability
why is CVS considered in AMA?
increased risk of:
- trisomy 13 = patau
- trisomy 18 = edwards
- trisomy 21 = down’s
when can CVS be done?
10-13wks
risks of CVS
invasive
carries risk of fetal demise
what is CVS
sampling of chorionic villous (made from pregnancy tissue) to directly test genes
what is the advantage of CVS over amniocentesis
CVS can be performed earlier in pregnancy and has a faster turnaround time
what are less invasive tests that can be used instead of CVS or amniocentesis?
cell-free fetal DNA
what is percutaneous umbilical blood sampling (PUBS)/cordocentesis used for?
definitive means of diagnosing and treating fetal anemia
when to use PUBS/cordocentesis?
MCA doppler positive (fetal anemia)
babe requires transfusion to survive
when can PUBS/cordocentesis be performed?
20wks < x < 32wks
