Threatened Abortion - Part 6
Yolk Sac and Amnion

how does visualization of the yolk sac help?

• One cannot use the presence or absence of a yolk sac to diagnose pregnancy failure. 
• The only utility of seeing a yolk sac is that it changes the follow-up interval
  • If NO embyro and NO yolk sac (MSD < 25 mm) Consensus panel recommends 2 week follow-up
  • If NO embryo and yolk sac PRESENT (MSD < 25 mm) Consensus panel recommends 11 day follow-up

important facts about the embryo and amnion

• Embryo visualization ALWAYS precedes amnion visualization
• Also, in the 1st trimester, the crown rump length fills the amnion from edge to edge

WHAT IS THE AMNION SIGN AND WHAT IS THE SIGNIFICANCE?

• If you can see the amnion and NO embryo, this has a 100% PPV for pregnancy failure
• The Consensus Conference did NOT adopt this criterion for pregnancy failure

what is the expanded amnion sign and what is the significance?

• Any embryo surrounded by amnion should have a visible heart beat
• This sign led to the ability to diagnose demise in embryos < 7 mm
• In fact, this sign had a 100% PPV of pregnancy failure in embryos < 5 mm.
• Also, the Consensus Conference did NOT adopt this criterion for pregnancy failure