serum integrated screening

Mary898
Hi ladies, 
Anyone had serum integrated screening test? It is two blood test between 10-14 weeks and 15-20 weeks. They combine both of them and make the risk assesment. My doc says I don't need NT scan bc i'm no risk and serum integrated is enough for me. What do you all think? I heard NT scan can detect heart diseases as well...so i'm pretty confused.