<prompt> USG can diagnose all except:AnencephalyNeural tube defectPlacenta preDowns syndrome  <response>: D i.e. Downs Syndrome In anencephaly, absece of vault. In NTD, presence of meningo-myelocoel In placenta pre location of placenta seen by USG confirms the diagnosis. Although on prenatal US increased nuchal fold thickness, and reduced length of femur humerus are suggestive of Downs syndrome but the diagnosis is confirmed by chromosomal study trisomy of 21st autosome either by amniocentesis or chronic villous sampling. 