screening in pregnancy Flashcards
when is diagnostic testing indicated
following prenatal test, if family history
when can CVS be performed and what is the advantage
11 weeks- so option of abortion is easier at this stage
what is done prior to CVS
ultrasound to confirm pregnancy and location of placenta
what are sampled in CVS
trophoblastic cells for karyotype (placenta)
how long do results take
2 days for karyotype, 3 weeks for enzyme and gene probe analysis
what happens to the genes
PCRd or cultured- culture is more accurate and info on all abnormalities
risk of miscarriage in CVS
2-4%
how is needle inserted in CVS
transabdominally or transcervically
when is amniocentesis performed
15-16 weeks
miscarriage amniocentesis
1% (5 if early- 10-13 weeks)
what is measures on amniocentesis
Amniotic fluid AFP and cells in fluid are cultured for karyotyping
how long does cell culture take in amniocentesis
3 weeks
what screening is recommended >20weeks
cordocentesis
what are early scans good at looking at
CNS, neck, GI, renal
what might fluid accumulation in the neck at 10-14 weeks show
fetal heart failure, anomaly of heart and vesels.
what happens to risk of abnormality with greater extent of fetal nuchal translucency
increases
what is nuchal translucency screening
used to see who may benefit from more invasive CVS, amnio.
other soft markers for downs
fetal nasal bone appearance, Doppler velocity - ductus venosus and tricuspid regurg
AFP as a marker
maternal AFP at 17 weeks- in 10% with high AFP there is a fetal malformation. decreased- chromosomal
what is the combined test in Downs tests
nuchal translucency, BHCG, PAPP-A (pregnancy associated plasma protein), and womans age
what is the integrated test in Downs tests
NT + PAPP-A in first trimester, quadruple test in 2nd trimester
what is the quadruple test
maternal AFP + unconjugated estriol + BHCG + inhibin-A + womans age in 2nd trimester
when is NT and serum tests done for Downs
11 weeks (10-13+6)
