IPS 1 (Ultrasound and blood work)

I'll be 12 weeks exactly on Tuesday October 28th and get to see my wee alien! I'm ecstatic! I can't wait. I'm opting to do the IPS test (nothing invasive-just an ultrasound and bloodwork). I did it almost 5 years ago when I was pregnant with our first son. But I don't remember having to go back for blood work 4 weeks after the origional ultrasound and blood work. Is this something new that has only started in the last 4 years or am I just simply losing my mind? Maybe I'm just too excited about getting to see my little babe again! TIA ladies!!