Amniocentesis/CVS GTG Flashcards
What is the risk of miscarriage after amniocentesis (amnio) or chorionic villus sampling (CVS)?
The risk of miscarriage after amniocentesis or CVS is less than 0.5%. For twins, the risk is around 1%.
Why should amniocentesis not be performed before 15 weeks of pregnancy?
Amniocentesis should not be performed before 15 weeks due to a higher risk of pregnancy loss, potential for talipes equinovarus (clubfoot), the possibility of multiple needle insertions, and the potential for false negatives.
Why is CVS not recommended before 10 weeks of pregnancy?
CVS should not be performed before 10 weeks because it carries a risk of oromandibular and limb defects.
What is the ideal gestational window for performing CVS?
The ideal gestational window for performing CVS is between 11 weeks and 0 days, and 13 weeks and 6 days.
What considerations should be taken into account before performing amniocentesis or CVS in cases of maternal viral infections?
The risk of blood-borne virus (BBV) transmission should be considered before performing an amniocentesis or CVS. HIV transmission risk is higher from mother to child if the mother is not on HAART (Highly Active Antiretroviral Therapy) and has a high viral load. For Hepatitis B, there is no increase in transmission if the viral load is low. Hepatitis C does not show reported mother-to-child transmission.
What should be done if amniotic fluid is cloudy or purulent during amniocentesis?
If the amniotic fluid is cloudy or purulent, it should be sent for microbial analysis, and antibiotic treatment may be considered.
What are the risks associated with amniocentesis or CVS?
Risks include: Second sampling: up to 6% of cases. Maternal cell contamination: 1-2%. Rapid test failure: 2%. Failed cell culture: 0.5-1%. Placental mosaicism (in CVS): less than 2%. Blood-stained sample in amniocentesis: 0.8%. Severe infection or fetal injury: rare.
What should be done in multiple pregnancies to ensure accuracy during amniocentesis or CVS?
In multiple pregnancies, fetal mapping must be done to identify each fetus reliably before proceeding with amniocentesis or CVS.
What is the risk of pre-term labor with third-trimester amniocentesis?
There is a 3-4% risk of pre-term labor before 34 weeks when performing amniocentesis in the third trimester.
What is the chance of cell culture failure in third-trimester amniocentesis?
There is a 10% chance of cell culture failure in third-trimester amniocentesis.
