I had my 13 week scan for my twins the doctor says that there is a possibility that they are in the same sac if identical. Meaning the cords can get tangled. We all swear there was a membrane before but now its not there or its hiding. Its scary to see a doctor search for words. A month ago it was news its twins now its news that there could be complications. So I maybe a future nicu momma and im scared. So I have to wait another month for another sono to get more answers.