Table 1

Antenatal Tests
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.

Aksoy BMC Medical Ethics 2001 2:3 doi:10.1186/1472-6939-2-3