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Table 1 Antenatal Tests

From: Antenatal screening and its possible meaning from unborn baby's perspective

Type of test

Detectable conditions

Stage of pregnancy

Invasive: mother only

  

MSAFP

  

Estimation of maternal serum

Neural tube defects; Down's

16th-18th week.

alphafetoprotein in maternal

syndrome.

 

blood.

  

Combined maternal blood

  

test

  

Estimation of MSAFP, chorionic

Down's syndrome.

16th-18th week.

gonadotropin and/or

  

unconjugated oestriol.

  

Invasive: both fetus and

  

mother

  

Amniocentesis

  

A test involving the insertion,

Chromosomal disorders; a

12th-14th week.

through the mother's abdomen,

number of hereditary disorders

 

of a fine needle into the

caused by a single gene; neural

 

amniotic sac and the removal of

tube disorders.

 

amniotic fluid.

  

Chorion biopsy

  

A test involving the introduction

Chromosomal disorders; a

8th-12th week.

through the mother's vagina or

number of hereditary disorders

 

abdomen of a needle into the

caused by a single gene.

 

womb and the removal of tissue

  

surrounding the fetus.

  

Fetoscopy

  

A test involving the introduction

Chromosomal disorders;

16th-18th week.

through the mother's abdomen

disorders detectable by fetal

 

of an instrument enabling the

blood sampling; malformations.

 

examiner to see the fetus.

  

Cordocentesis

  

A test involving the insertion of

Chromosomal disorders;

15th week

a needle through the mother's

disorders detectable by fetal

onwards.

abdomen (where the umbilical

blood sampling.

 

cord of the fetus is attached to

  

the placenta) and then the

  

removal of fetal blood.

  

Non-invasive

  

Ultrasound scan

  

An instrument is passed over

Fetal growth and development;

Any time but often

the mother's bare abdomen

multiple pregnancy;

about the 16th

and a picture of the fetus is

malformations, including neural

week to check

produced on a screen.

tube defects.

dates and

  

development.

Radiography

  

The mother's abdomen is X-

Skeletal abnormalities requiring

20th week

rayed. This is hardly ever done

a picture of the whole skeleton.

onwards.

today.

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