Amniocentesis Essay

Amniocentesis allows for fetal DNA in the amniotic fluid to be analyzed for chromosomal abnormalities. This can be done in response to abnormal serum genetic screening, an abnormal ultrasound finding, or in order to specifically test for a genetic condition for which a patient or partner is a carrier, including autosomal recessive, autosomal dominant, X-linked conditions or microdeletion/microduplication syndromes. This analysis of the fetal DNA is only possible with diagnostic testing via amniocentesis or chorionic villus sampling (CVS). One advantage of amniocentesis over CVS, however, is the ability to directly analyze fetal DNA. This avoids the potential issue of confined placental mosaicism that may be encountered in CVS samples. In 1-3% of CVS samples, chromosomal mosaicism is seen[13]. This mosaicism is usually confined to the placenta, however is also present in the fetus in 10% of cases. In all cases of mosaicism on CVS, amniocentesis is recommended in order to determine whether it is confined to the placenta or is seen in the fetus as well.

Another important application for amniocentesis that deserves its own attention is in twin gestations. It has been previously shown that twin gestations are at an increased risk for chromosomal abnormalities. Further, the rate of multiple births is increasing. Between 1980 and 1999, the overall multiple birth ratio increased 59% and by 1999 multiples accounted for 3% of all

Whether there are ultrasonographic signs that a fetus has been affected by one of these viruses or maternal serum indicates infection, amniocentesis can be performed. Polymerase chain reaction studies for these viruses should then be performed on the amniotic fluid obtained[27]. This information is essential to guide further fetal assessement and possible intrauterine treatment, depending on the clinical