Fetal Screening Flashcards
List the screening methods and indications of genetic abnormalities during pregnancy
Perform in case of advanced maternal age, history of chromosomal issues,abnormalities in pregnancy:
○ Chorionic Villus Sampling (CVS): 10-12 weeks - taken sample from fetal
placenta to karyotype
○ Amniocentesis: 16 - 20 weeks, fetal cells in amniotic fluid are extracted and cultured for karyotyping + AFP levels
○ Percutaneous umbilical cord blood sample: 20+ weeks, take blood from
umbilical cord to determine fetal Ht in Rh isoimmune, chromosomal analysis, give blood transfusions if nec. Dangerous, 3-5% preg loss
○ U/S - 1st 11-13 week, 2nd 18-20 week and 3rd 28-32 week ultrasound check
for abnormalities
○ AFP - decrease in Downs and Patau, increased in neural tube defects
List the types of examinations performed during the 3rd Trimester of Pregnancy
-US, CTG, AFI Doppler artery check, nonstress test.
○ Fetal movements should be 10 movements in 1 hour.
○ Non stress test- to check current placental function, take fetal heart rate
(normal 110 to 160) look for accelerations, variability. Do biophysical profile if
not acceptable
○ Amniotic fluid index : Sum of linear measurements in cm of the amniotic fluid
in 4 quadrants. Oligohydramnios if < 5 cm, polyhy is > 23 cm
○ Doppler artery check :
■ Umbilical artery systolic/diastolic (S/D) ratio: indirectly measures
resistance within placental vessels; fetuses with absent or reverse
end-diastolic flow should be delivered asap
■ Fetal middle cerebral artery (MCA): decreased placental perfusion
generally spares fetal brain; shunting to brain causes increase of
diastolic and mean blood flow velocity in MCA
■ Ductus venosus: fetus with highly abnormal ductus flow at risk of
impending acidemia and death
