Amniocentesis & CVS Flashcards
In UK , choice of invasive prenantal testing offered
- 5 % of pregnant population
- 30 k per annum
amniocentesis or CVS more common?
amniocentesis
what is normal or early amniocentesis?
<15 completed weeks, normal 15+0 onwards mostly 16-18 weeks 20 gauge needle real time scan
CVS timing
way
- 11+0 to 13+6 weeks
- Aspiration / Biopsy TVS or TAS
- Additional miscarriage following amniocentesis
- Total post amniocentesis pregnancy loss (background+ procedure related)
1 %
1.9 %
Additional miscarriage following CVS
Slightly higher than amniocentesis, 15+0 onwards
Transplacental amniocentesis
15 %
Blood stained amniotic fluid
0.5 %
Early amniocentesis <15+0, complications
- Higher fetal loss rate
- Increase incidence of fetal talipes
- respiratory morbididty
Early CVS <10+0 weeks, complications
reports of oromandibular hypoplasia & isolated limb disruption defect but reassuring reports later
still not recommended due to difficulty b/c of
- small uterus and
- thin placenta
what kind of consent from for Amniocentesis & CVS
- Consent DH form 3
- Reason
- Type of results
- Storage
- Quality control
- Local/national loss rate
- Accuracy /limitation test: culture failure rate
- Reporting times
- Method of communication
- Indication seeking help
- Anti-D
How many procedures (Amniocentesis & CVS) per year for competency maintenance
- Arbitrary Number : at least 30 per annum
- Feasible most clinical place
- if less than audit in place
- MRC trial: No evidence increase procedure improve safety
Postgraduate training for Amniocentesis & CVS
how many to be performed?
not Numeric goal but competency based assessment (interaction+procedure)
A- sub-specialty training maternal & fetal medicine
B- RCOG- Fetal medicine (ATSM) not RCOG log book but advanced training skill module.
C- Other international equivalent
when to audit for operator competence for Amniocentesis & CVS
Loss rate:
- 5 % for amnio
- 9 % for CVS
Second insertion for amnio 8 %
sampling failure for CVS: 6 %
Gold standard for CVS
sampling failure
Pregnancy loss
3 %
3 %
Amniocentesis technique
- max diameter 20 (0.9 mm) gauge needle
- Angle: some, no robust data
- anesthesia local: 4 % in UK
real time scan( mapping+ cord insertion) so
- Avoid blood staining (0.8 - 2.4 %) interfere with culture
- avoid fetus, bowel, placenta,
- Avoid dry tap
If transplacental cant be avoid then thinnest part, avoid cord insertion
CVS technique
- Local anesthesia: 98 % in UK, should be used
- Technique, familiar
Transabdominal:
Needle size: 18 gauge- 20 gauge
double needle: 17/19 gauge- 18/21 gauge
Method of aspiration: neg pressure by syring/vaccum aspirator or biopsy forceps
Trancervical:
normally aspiration cannula used
some evidence: small forceps better than aspiration cannula, but not strong enough to change practice
- real time scan: Consensus
multiple pregnancy, amniocentesis
who, challenges and how
- Performer able to selective TOP b/c right Labelling
- Uterine mapping
- most use 2 puncture sites: miscarriage higher than singleton by both 1/2 puncture
multiple pregnancy, amniocentesis: pregnancy loss rate
1.8 %,, 1/56
CVS in dichorionic
- Controversial
- Cross contamination, false +, false _ve
- To minimize to separate needles
- Only after detailed counselling
3rd trimester amniocentesis: Indication
- Late karyotyping - most common
- Detection of fetal infection with PPROM
3rd trimester amniocentesis: Outcome
- Multiple attempt: >5 % sampling- more common 3rd tri
- Blood stained fluid: 5-10 % cases-more common 3rd tri
- With PPROM, failure rates higher
- Suggestion culture failure : 9.7 %
3rd trimester amniocentesis:Complications
Serious rare - Suggestion: 0.7 % proccedure related delivery No increase in 1 - Urgent birth 2- Abruption 3- PROM 4- 5 min apgar <7
3rd trimester amniocentesis: risk of emergency delivery
no significant risk of emergency delivery
