Amniocentesis

<Procedures>

<Index>

 

Rationale

-  Antenatal genetic test on amniotic fluid

-  Looks for Down Syndrome, CF, neural tube defects..

 

Amniotic Fluid

 

Features

-  Performed between weeks 15 -18+ pregnancy

 

Indications

- Offered to women

-  > 37 years

-  Indications of Down Syndrome from blood tests & nuchal transluceny

-  W previous pregnancies effected by genetic abnormalities (CF, Down Syndrome..)

-  Family Hx of hereditary disorders (CF, thalassaemia..)

 

Complications

-  0.5% risk of miscarriage

-  APH

 

Procedure

-  Ultrasound performed 1st

-  Confirm gestational age & placental site

-  Best performed w full bladder

-  Can be performed transabdominally or transvaginally

-  Expose abdomen

-  Clean abdomen w antiseptic (betadine)

-  Inject site w local anaeshtetic (lidnocaine)

-  Wait for anaesthetic to take effect

-  Inesert needle into amniotic fluid w ultrasound guidance

-  Aspirate amniotic fluid into syringe (15-20ml)

-  Repeat ultrasound to confirm foetal stability

-  Patch Amnio site w dressing

 

Amniocentesis

 

Results

-  Detects: Down Syndrome, Trisomy 18, Edwards Syndrome, spina bifida, anencephaly

-  Rehusus antibodies: maternal & foetal

-  Gender

-  Cannot detect all birth defects

-  Can determine maturity of foetal lungs