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Sampling the fluid from the amniotic cavity after about 14 or 15 weeks of pregnancy. Cells from the fetus can be set up in culture for a karyotype, or for special diagnoses can be examined more quickly by fluorescent in situ hybridization (FISH), comparative genomic hybridization (CGH) or by polymerase chain reaction (PCR). Other substances in the amniotic fluid (such as alpha fetoprotein, or AFP) can be measured to indicate whether the fetus is normal or not.
Copyright © 1998 Robert
Jansen, WH Freeman / Scientific American Books, and Allen &
Unwin. |
