Mehl. trisomy diagnostic modalities + UW cfDNA 02-13 (1) Flashcards
amniocentesis. when?
15-18 (gali but 15-20) weeks
amniocentesis. how performed?
Thin needle is inserted through the abdominal wall, under ultrasound guidance, into the
amniotic sac surrounding the fetus. A small amount of amniotic fluid, which contains fetal
cells, is drawn out. The collected cells are analyzed for chromosomal abnormalities.
amniocentesis. what is risk for iatrogenic abortion?
Risk of iatrogenic abortion is up to ~1/1,000, depending on location and expertise.
amniocentesis. how accurate detect trisomies?
> 99%
CVS. abrev?
Chorionic villus sampling.
CVS. when performed?
10-13 weeks.
CVS. how performed?
Ultrasound-guided needle is inserted transcervically or -abdominally to remove a sample
of cells from the chorionic villi of the placenta, which have the same genetic material as
the fetus, allowing for chromosomal analysis.
CVS. what is risk for iatrogenic abortion?
higher than amniocentesis, at ~1/100-200.
CVS. accuracy?
> 99% accurate for detecting trisomies.
CVS. why some people choose it over amnio?
because it allows for diagnosis of trisomies earlier in pregnancy, thereby time for parental decision making.
Cell-free DNA; aka non-invasive prenatal testing (NIPT). when performed?
after 10 weeks
Cell-free DNA; aka non-invasive prenatal testing (NIPT). how performed?
Involves taking a blood sample from the pregnant woman which contains fragments of
DNA from both her and the fetus. Laboratory techniques then analyze the fetal DNA
fragments for chromosomal abnormalities.
Cell-free DNA; aka non-invasive prenatal testing (NIPT). accuracy?
- > 99% accurate, but false-positive rate compared to amniocentesis and CVS. As a result, cfDNA is considered to be a screening, rather than diagnostic test.
Cell-free DNA; aka non-invasive prenatal testing (NIPT). if positive, what to do?
Positive results are
followed up with amniocentesis or CVS.
Cordocentesis. when performed?
after 18 weeks
Cordocentesis. how performed?
Transabdominal ultrasound-guided needle insertion into umbilical cord to retrieve fetal
blood.
Cordocentesis. indication?
Classic indication is to diagnose fetal hematologic abnormalities such as anemia.
Cordocentesis. Not typically done for chromosomal investigations, but allows for rapid karyotyping if a quick chromosomal analysis is required, especially if amniocentesis or CVS results are
inconclusive or if there’s a need for faster results than these tests can provide.
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UW. cfDNA. Indications? 5
Maternal age >=35 (is advanced aged)
Abnormal maternal serum screening test (eg quadruple screen)
sonography shows aneuploidy findings
prior pregnancy with aneuploidy
parental-balanced robertsonian translocation
UW. cfDNA. applications?2
screening for trisomy 21, 18, 13
fetal sex determination
Women age ≥35 (ie, advanced maternal age) are at increased risk of fetal aneuploidy and are offered cell-free fetal DNA testing (cffDNA) of maternal plasma.
.
Noninvasive cffDNA testing can be performed at ≥10 weeks gestation and has a high sensitivity and specificity for detecting trisomy 21 (Down syndrome), trisomy 18 (Edward syndrome), and trisomy 13 (Patau syndrome). It can also identify the fetal sex and some sex chromosome disorders.
.
cffDNA normal –>?
no additional evaluation
cffDNA abnormal –>?
Abnormal results are confirmed by fetal karyotyping via first-trimester chorionic villus sampling or second-trimester amniocentesis.
The initial prenatal visit uses a combination of maternal history and prenatal testing to identify patients at risk for obstetric complications. Prenatal testing can be routine (eg, HIV screen, maternal blood typing) or risk based.
tai cffDNA - buvo in case risk based, nes duota moteris, kurios amzius 40 metu
.
β-hCG levels have no clinical value once an intrauterine pregnancy is confirmed on ultrasound.
Quantitative β-hCG levels are indicated in patients with a pregnancy of unknown location because abnormal levels may indicate an ectopic pregnancy
