This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
Which of the following is done for screening of Down's syndrome in first trimester? 
Select and explain. 
A. Beta HCG and PAPP-A, B. Unconjugated estradiol and PAPPA, C. AFP and Inhibin A, D. AFP and Beta HCG
A: Beta HCG and PAPP-A
Answer: A: Beta HCG and PAPP-A 
Explanation: Ans: A. Beta HCG and PAPP-A1st trimester aneuploidy screening:Human chorionic gonadotropin (either intact or free (b-hCG).Pregnancy-associated plasma protein A (PAPP-A).Fetal Down syndrome in 1st trimester:Higher serum free beta-hCG level.Lower PAPP-A levels.Trisomy 18 & 13:Lowered levels of both HCG PAPPP-A.2nd trimester analytes:Serum integrated screening.Accuracy of aneuploidy detection:Greater on combination with,Sonographic NT measurement.