One Baby, One Sac - Twins?



I went for my first scan at 7 weeks; it turns out I was 6 weeks 4 days. I had a vaginal scan were there was one baby and one sac. The baby was healthy with a good heartbeat. I had bleeding and had to go to ER. The bleeding wasn't bad but went to get checked out to be on the safe side.

They booked me for another scan at 7 weeks 4 days. At this scan they found 2 sacs and one baby. I've got to go back in two weeks times as they're unsure if its twins.

What do you think? Thanks.


Early ultrasound often shows that twins have formed. Many times women come to the ER because of bleeding. An ultrasound is ordered and two sacs are seen with a fetal pole and heartbeat in only one. Because of the high resolution technology in ultrasound, we now know that twins form more often than women knew. A collapsing gestational sac or an empty gestational sac might be seen next to a normally developing sac which would be the cause of the vaginal bleeding.

It would be unusual for a second gestational sac that was not appreciated at the time of a 6 w 4d ultrasound sound, to present itself in 3 weeks with a viable fetal pole. The more likely scenario would be a twin sac that has not developed properly.

With Regards,
Jane Foley RDMS

Jane Foley

Jane Foley has worked as a Sonographer (Ultrasound Technologist) since 1979. Jane has lived and worked in many parts of the world including Saudi Arabia. She is a Registered Diagnostic Medical Sonographer or RDMS. She pulls a wealth of information from her experience in the field of Radiology and her interactions with such a broad cross-section of cultures she has visited. She now makes her home on the island of Maui with her English husband, Michael.