This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnosis of Pregnancy, Subject name: Gynaecology & Obstetrics
In 1st trimester, all of the following can be well appreciated, except 
Select and explain. 
A. Nuchal Translucency, B. CRL, C. Hydrocephalous, D. Anencephaly
C: Hydrocephalous
Answer: C: Hydrocephalous 
Explanation: 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