AMNIOCENTESIS Amniocentesis is the most commonly performed procedure used to diagnose fetal aneuploidy and other genetic conditions. Indications Diagnosis of fetal genetic disorders Congenital infections Alloimmunization Assessment of fetal lung maturity Therapeutic for polyhydramnios The most common types of prenatal diagnostic tests are: Chromosomal Micro Array to assess copy-number gains or losses karyotype analysis to test for aneuploidy, Fluorescent In Situ Hybridization ( FISH ) to identify gain or loss of specific chromosomes or vchromosome regions It is ideally done at 16-18 weeks.Early amniocentesis can be done between 13-15 weeks.