Potentially silly ultrasound question

curlylocks3

But since you all seem pretty familiar with reading ultrasounds, I thought I'd throw it out there!

I know twin A is the one closest to the cervix, but what if they seem equal? I've only had one US so far (6w3d) and it was transvaginal, and the sacs appear to be totally side by side in it. So, are they just arbitrarily assigned "a" and "b" or do they wait til later for that?

katekat8721

I'm glad you asked Curls, I had the same question. My u/s yesterday it looked like they were side by side. I'm guessing they move with they grow a little bigger?

BTW, I LOVE your penguin siggy with Mumble and Hugsy - so, so cute!

ballygirl

It may take a little mire time to determine which one is closest to the cervix. On my early (6 & 7 week) ultrasounds they just assigned an arbitrary a or b. It became more clear which was lower down later on but I don't remember exactly when.

curlylocks3

Thanks @ballygirl!
And thank you @katekat8721! I had fun making it

megs2011

I'm of not help.. I had my first u/s at 10 weeks so there was a definitely baby closest to the cervix. However, they did seem to think they switched spots towards the end and "B" came out first... kind of funny.

kimberm0511

Mine switched. When I was that early in the pregnancy, they named the one they thought was closest "A", but they wound up switching them later on since the other one has been closest to the cervix.

sunkiss674

In my case I'm having di/di boys and I know I should listen better but I think they said something about the position of the placentas too. One of my ultrasounds the babies were laying on top of each other and she looked for the placenta and which baby they went to.

carrotcake06

In the beginning, mine measured pretty much the exact same and were side by side, so to speak (di/di). I asked at my 13w u/s and I was told that a and b are assigned at each u/s based on who's closest to the exit. That at around 19-24w available real estate to flip around so much starts to come at a premium, so usually a stays a and b stays b. If that makes sense.

My baby a was breech from 20w+. At an u/s around 32w, I expressed my continued desire for a vag birth and was told that if baby b stayed vertex and dropped into position below baby a, that since b would then be closest to the cervix and vertex, I could attempt a vag delivery. It was a moot discussion as baby a stayed in position and his cord prolapsed, so c/s it was.

Mrs. Alice

It may vary from each u/s tech or OB. I had my first u/s at 10 weeks and my OB refused to assign and "A" and "B" at that point.  I don't think she even did at 14 weeks either. My MFM was the one who assigned and "A" and "B" at my 18 weeks a/s and they stayed in those positions until birth.  My twins were mo/di. 

curlylocks3

Thanks for the feedback everyone! 
To anyone else who stumbles on this or is wondering (@katekat8721)- my OB said she wasn't going to name them A or B yet and for now they're just "left" and "right". 

katekat8721

Thanks! @curlylocks3

KatieGummow

ballygirl said:

It may take a little mire time to determine which one is closest to the cervix. On my early (6 & 7 week) ultrasounds they just assigned an arbitrary a or b. It became more clear which was lower down later on but I don't remember exactly when.

Same!