I'm trying to figure out the odds of my twins being identical or not and I haven't found much help on the Internet. My first ultrasound at 12 weeks the tech told me that they were in separate sacs. Second ultrasound at 13 weeks different ultrasound location said same sac but separated by a membrane. They have separate placentas confirmed by both locations. I'm just confused by the one sac vs separate sacs. I have a dr appt next week I will be 17 weeks and will ask the dr what they think then as well just collecting info. Thanks for any info.