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Bushra's obstetrics > Amniocentesis & CVS > Flashcards

Amniocentesis & CVS Flashcards

1
Q

In UK , choice of invasive prenantal testing offered

A
  • 5 % of pregnant population

- 30 k per annum

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2
Q

amniocentesis or CVS more common?

A

amniocentesis

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3
Q

what is normal or early amniocentesis?

A 
<15 completed weeks, 
normal 15+0 onwards
mostly 16-18 weeks
20 gauge needle
real time scan
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4
Q

CVS timing

way

A
  • 11+0 to 13+6 weeks

- Aspiration / Biopsy TVS or TAS

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5
Q
  • Additional miscarriage following amniocentesis

- Total post amniocentesis pregnancy loss (background+ procedure related)

A

1 %

1.9 %

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6
Q

Additional miscarriage following CVS

A

Slightly higher than amniocentesis, 15+0 onwards

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7
Q

Transplacental amniocentesis

A

15 %

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8
Q

Blood stained amniotic fluid

A

0.5 %

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9
Q

Early amniocentesis <15+0, complications

A
  • Higher fetal loss rate
  • Increase incidence of fetal talipes
  • respiratory morbididty
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10
Q

Early CVS <10+0 weeks, complications

A

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
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11
Q

what kind of consent from for Amniocentesis & CVS

A
  • 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
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12
Q

How many procedures (Amniocentesis & CVS) per year for competency maintenance

A
  • 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
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13
Q

Postgraduate training for Amniocentesis & CVS

how many to be performed?

A

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

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14
Q

when to audit for operator competence for Amniocentesis & CVS

A

Loss rate:

  • 5 % for amnio
  • 9 % for CVS

Second insertion for amnio 8 %
sampling failure for CVS: 6 %

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15
Q

Gold standard for CVS
sampling failure
Pregnancy loss

A

3 %

3 %

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16
Q

Amniocentesis technique

A
  • 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

17
Q

CVS technique

A
  • 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
18
Q

multiple pregnancy, amniocentesis

who, challenges and how

A
  • 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
19
Q

multiple pregnancy, amniocentesis: pregnancy loss rate

A

1.8 %,, 1/56

20
Q

CVS in dichorionic

A
  • Controversial
  • Cross contamination, false +, false _ve
  • To minimize to separate needles
  • Only after detailed counselling
21
Q

3rd trimester amniocentesis: Indication

A
  • Late karyotyping - most common

- Detection of fetal infection with PPROM

22
Q

3rd trimester amniocentesis: Outcome

A
  • 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 %
23
Q

3rd trimester amniocentesis:Complications

A 
Serious rare
- Suggestion: 0.7 % proccedure related delivery
No increase in
  1 - Urgent birth
  2- Abruption
  3- PROM 
  4- 5 min apgar <7
24
Q

3rd trimester amniocentesis: risk of emergency delivery

A

no significant risk of emergency delivery

25
Q

how many failed attempts of Amniocentesis & CVS to call experienced operator

A

2 failed attempts

26
Q

sources of infection in Amniocentesis & CVS

A

Avoidable by stanfdard practice

  • Bowel
  • Skin
  • US probe (cleaning vs degradation) so sterile bag till suitable process for probe decontamination available
  • US gel (separate sterile gel) (microbiological surveillance)
27
Q

severe sepsis risk with Amniocentesis & CVS

A
  • Likely to be < 1/1000
28
Q

screening for bloodborne viruses

  • for prenatal diagnostic procedures,
A
  • Infection-control risk + maternal–fetal transmission
  • not carried out without Blood-borne virus screening
  • No HIV: rapid test
  • women decline: inform & document (informed consent) vertical transmission
29
Q

For hepatitis B, Infection risk with Amniocentesis & CVS

A
  • risk of transmission of hepatitis B was very low.
  • ‘e’ antigen status may be important
  • recent evidence: maternal viral load more important
  • Invasive prenatal testing 1st/2nd trimester can be done
  • limitations of available data should be explained.
30
Q

For hepatitis C, Infection risk with Amniocentesis & CVS

A
  • no evidence that transmission is increased following amniocentesis.
  • Invasive prenatal testing 1st/2nd trimester can be done
  • limitations of available data should be explained.
31
Q

HIV transmission prevention in Amniocentesis & CVS

A
  • Review viral load and treatment regimens prior &
    consider delaying procedure until no detectable viral load if already on treatment.
  • Consider antiretroviral therapy if not yet on treatment
32
Q

HIV transmission risk with Amniocentesis & CVS

How much is risk?

A
  • 3rd trimester procedure: RR 4%
  • No treatment : 25 %
  • Mono/double therapy: 6.1 %
33
Q

Maternal RhD status with Amniocentesis & CVS

A
  • should be available or obtained in every case.
  • Prophylaxis with anti-D immunoglobulin
    must be offered following each procedure

Bushra's obstetrics (54 decks)

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