This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Physiology & Histology, Subject name: Gynaecology & Obstetrics
Single most important feature to diagnose fetal aneuploidy: 
Select and explain. 
A. Increased nuchal translucency, B. Absent nasal bone, C. Cystic hygroma, D. Abnormal ductus venosus flow
A: Increased nuchal translucency
Answer: A: Increased nuchal translucency 
Explanation: Ans: (a) Increased nuchal translucencyRef: Current Progress in Obstetrics and Gynecology, John Stud, Volume Page 17Ultrasound markers of fetal aneuploidy:Nuchal translucency is the single most powerful tool. More than 3 mm needs evaluationAbsence of nasal boneAbsence or reversal of flow in the ductus venosus on DopplerTricuspid regurgitationIncrease in frontomaxillary angle more than 85 deg