Hi. My LMP 22/04/2018. GA by LMP 5 wks. Mean sac diameter is 13 mm, corresponds to 6wks. No fetal pole but yolk sac noted at ultrasound measurement. Is it correct one or not. Below 5 weeks (exactly 4.3 was) it showing 13 mm sac. That to it is showing corresponds to 6wks. Please help me is it right or wrong.