2021 8 Amnio & CVS

Question 1

What’s the additional risk of miscarriage following amnio or CVS?

Answer 1

Below 0.5%

Question 2

At what gestations should amniocentesis not be offered?

Answer 2

Before 15/40

Question 3

At what gestations should CVS not be offered?

Answer 3

Before 10/40
Ideally 11/40 to reduce technical challenges

Question 4

What is the additional risk of miscarriage for twin pregnancies following amnio or CVS?

Answer 4

1%

Question 5

What results should be reviewed when considering amnio or CVS?

Answer 5

Blood borne viruses screen
Viral load
Antigen test results

Question 6

For what reasons are amniocentesis & CVS offered?

Answer 6

Higher chance aneuploidy screening
Fetal structural anomaly
Known risk of inherited genetic disease

Question 7

What tests have reduced the demand for amnio & CVS?

Why is there still demand though?

Answer 7

National combined aneuploidy screening
Cell free DNA testing maternal blood

Only definitive diagnostic test

Question 8

At what gestations is CVS typically offered?

Answer 8

11+0 to 13+6
(Consider at 14+0 to 14+6)

Question 9

What should be included in the consent process for amnio & CVS?

Answer 9

1. Procedure risks
2. Timing
3. Method of communicating results
4. Sample & tissue storage
5. Benefits
6. Alternatives
7. Option to opt out

Question 10

What options need to be discussed when chromosomal anomalies are identified?

Answer 10

Continuing & keeping the baby
Continuing & planning adoption
Continuing with view for palliative care
Ending the pregnancy

Question 11

When should antibiotics be considered following amnio or CVS?

Answer 11

Cloudy or purulent amniotic fluid
Clinical features of infection
In conjunction with microbial analysis

Question 12

What risks are associated with amnio & CVS?

Answer 12

1. 2nd sampling/repeat procedure (6%)
2. Blood-stained sample (0.8% amnio)
3. Confined placental mosaicism (<2% CVS)
4. Maternal cell contamination (1-2%)
5. Rapid test failure (2%)
6. Failed cell culture (0.5-1%)
7. Severe infection (rare)
8. Fetal injury (rare)
9. Maternal visceral injury (rare)

Question 13

What is required for training & maintaining good practice for amnio & CVS?

Answer 13

1. MFM subspecialty or ATSM
2. Sim training & direct supervision
3. At least 20 procedures a year
4. Comms skills training
5. Continuous audit
6. Seek support for difficulties
7. Review if annual loss rate >3%

Question 14

What are the risks of amnio before 15/40?

Answer 14

Higher risk of miscarriage
Talipes equinovarus
Multiple needle insertions
Failed culture
False negatives

Question 15

What are the risks for CVS before 10/40?

Answer 15

Oromandibular disruption
Limb reduction defects

More technically challenging before 11/40 as thinner, less developed placental tissue

Question 16

What are the considerations for amnio & CVS in multiple pregnancy?

Answer 16

1. Detailed counselling & mapping
2. Ability to perform selective termination if required
3. Additional 1% risk pregnancy loss
4. Specialist counselling services

Question 17

When should 3rd trimester amnio be considered?

Answer 17

1. Newly identified fetal structural anomalies
2. Suspected fetal infection
3. Fetal growth restriction

Question 18

What are the risks of 3rd trimester amnio?

Answer 18

PTL, low risk
Higher risk cell culture failure

Question 19

What are the BBV considerations in amnio & CVS?

Answer 19

1. Review screening tests for all
2. Delay until HIV status determined
3. MTCT very low if on HAART
4. Aim for undetectable viral load first
5. Hep B risk low if viral load <6.99 log10
6. Hep C no current evidence MTCT