What is the best way to detect abnormalities in the fetus?
No absolute test to detect fetal abnormalities exists; each test has advantages and disadvantages. The earliest possible abnormality detection tests are available only through in vitro fertilization programs. After IVF, the blastocyst can be sampled by removing one of its cells prior to placement into the uterus, a procedure called preimplantation genetic diagnosis. Experimental methods involve detecting fetal cells through the cervix or in the maternal blood stream and performing DNA analysis on these cells. The next earliest tests involve early ultrasound looking for fetal structural defects. In chorionic villus sampling (CVS), the physician obtains a small sample of placenta by passing a needle through the abdomen or the cervix. This is performed at 10-12 weeks gestation, and results are available in 24-48 hours. An amniocentesis, which acquires fetal cells in the amniotic fluid, can be performed at 14-18 weeks gestation with results available in approximately 9-10 days. Earlier amn
