GTG 8 - Amniocentesis and CVS Flashcards
Why has the rates of amniocentesis and CVS decreased over recent years?
Increase in combined screening and use of cell free DNA.
What tests should be carried out before undertaking an amniocentesis or CVS?
Blood Born Viruses and antigen testing. And ensure HIV status is known.
What considerations are taken into account for women with HIV on ART wishing to have an amniocentesis or CVS?
If on ART, there is a very low risk of transmission.
But aim to have undetectable viral load before procedure.
What is the risk of miscarriage following CVS?
0.5%
(1% in twins+)
Likely higher if congenital abnormality.
What is the risk of transmitting Hepatitis with CVS?
HepB: low risk if viral load <6.99 (increased with higher viral load).
HepC: no evidence of transmission risk.
When can CVS be carried out?
Not before 10/40.
Ideally 11+0 - 13+6
Consider 14+0 - 14+6 if required.
What are the risks associated with CVS?
- Need for repeat procedure (6%).
- Rapid test failure (2%).
- Placental mosaicism (<2%).
- Maternal cell contamination (1-2%).
- Failed cell culture (0.5-1%).
- Rarely: severe infection, foetal injury or vascular injury.
Why is CVS not carried out <10/40.
Risk of oromandibular disruption and limb reduction.
When can amniocentesis be carried out?
Not before 15/40
Ideally From 16/40
What are the risks of carrying out amnioncetesis <15/40?
Talipes equinovarus (clubfoot).
Need for multiple needle entries.
Failed cell culture.
False negative results.
What is the risk of miscarriage after amniocentesis?
1%
(additional 0.5%).
What are the risks associated with amniocentesis?
- Need to repeat procedure 6%
- Rapid test failure (2%)
- Maternal cell contamination (1-2%)
- Failed cell culture (0.5-1%)
- Blood stained sample (0.8%)
- Rare: severe infection, foetal injury and maternal vascular injury.
What are the additional risks associated with amniocentesis in the third trimester?
- 10% cell culture failure (increases with gestation).
- 3-4% pre term labour (limited studies).
