This test is done in the 14th to 18th week of pregnancy. A small amount of the amniotic fluid is taken from the uterus and then sent to a laboratory to be studied. Cells from the developing baby are found in the amniotic fluid.
Neonatal Tests
No anaesthetic is required, and a result is usually obtained in about three to four weeks. When the test is carried out by an obstetrician experienced in the technique, the risk of a miscarriage related to the test is about 1 per cent (occurring in 1 in 100 pregnancies).
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Prenatal Diagnosis
This test must be done in the 10th to 12th week after the first day of the mother's last menstrual period. The test is done by looking at cells taken from the placenta.
Prenatal Tests
No anaesthetic is required, and a test result is usually available in two to three weeks.
When the test is carried out by an obstetrician experienced in the technique, the risk of miscarriage related to the test is about 2 per cent (occurring in 1 in 50 pregnancies).
Prenatal Tests
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Prenatal Diagnosis
false negative rate
- The proportion of pregnancies that will test negative given that the congenital anomaly is present.
false positive rate
- The proportion of pregnancies that will test positive given that the congenital anomaly is absent.
negative predictive value
- The probability that a congenital anomaly is absent given that the prenatal screening test is negative.
positive predictive value
- The probability that a congenital anomaly is present given that the prenatal screening test is positive.
pre-implantation genetic diagnosis
- (PGD) a screening procedure for embryos produced through in vitro fertilisation (IVF)
for genetic diseases that would generate developmental abnormalities or serious postnatal diseases.
prenatal screening sensitivity
- (detection rate) The probability of testing positive on a prenatal screening test if the congenital anomaly is present.
prenatal screening specificity
- The probability of testing negative on a prenatal screening test if the congenital anomaly is absent.
Prenatal Tests
Embryo Website |
Prenatal Diagnosis
