In 1st trimester, all of the following can be well appreciated, except

Crown rump length- Ideal time to measures CRL is 7 - 10 weeks Anencephaly - Earliest anomaly to be detected on USG , can be defected earliest by 10 weeks. Nuchal translucency - sonographic marker of down syndrome / aneuploidy in 1st trimester (seen at 10-12 weeks). Hydrocephalus can be seen around 20 - 24 weeks or beyond when fetal cranium and brain stas growing and the CSF stas establishing