Question about 5 week u/s... what comes first gas sac or yolk.....

I had an u/s done today at 5 weeks even and all there was was a small gas sac that looked like the one in the pic below. Is this ok for 5 weeks? Does it look to small? What comes first the yolk sac or gas sac? Im so worried!

http://pregnancy.about.com/library/ultrasounds/4wsac.jpg

[mama2kja]

http://www.babyjava.net/images/ultrasound-sac.jpg

[Darkestlight]

At my 5wk u/s all that was seen was a yolk sac. I'm not sure which comes first honestly. I think we had problems seeing things on my u/s because my uterus was tilted in the beginning of my pregnancy.

[chellybeans]

the gestational sac is first, that is what everything grows in, then the yolk sac it is what feeds the forming fetus until the placenta is functioning on its own. :)

[mama2kja]

bump

[melqtpie2003]

I HAD A U/S WHEN I WAS 5W 6D & THE GESTATIONAL SAC LOOKED LIKE THE ONE IN YOUR ULTRASOUND.  I ALSO HAD A VERY SMALL YOLK SAC THAT LOOKED LIKE A LITTLE WHITE SHADOW.  I BET IF YOU WAITED A COUPLE MORE DAYS YOU WOULD BE SUPRISED BY A LITTLE YOLK SAC.  IT'S CRAZY HOW MUCH CHANGE 1 SIMPLE WEEK CAN DO.  BABIES ARE AMAZING LITTLE ANGELS THAT CHANGE EVERYDAY...KEEP YOUR HEAD UP AND CONGRATULATIONS ON YOUR LITTLE MIRACLE...I AM 7 WKS 4D...WE ARE NOT THAT FAR APART