This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Antenatal Care & Assessment of Fetal Well Being, Subject name: Gynaecology & Obstetrics
Which Congenital malformation of the fetus can be diagnosed in first trimester by ultrasound? 
Select and explain. 
A. Anencephaly, B. Iniencephaly, C. Microcephaly, D. Holoprosencephaly
A: Anencephaly
Answer: A: Anencephaly 
Explanation: Ans. A. AnencephalyUltrasound can be used to detect anencephaly as early as 10 weeks' gestation. With an abnormal head/trunk ratio and abnormally large orbits, the absence of the superior vault is associated.The length of crown-rump is normal in most anencephalic fetuses.