Amniotic membrane

Case contributed by Dr Matt A. Morgan


Normal first trimester fetal ultrasound corresponding to 8 weeks 5 days

Annotated image

The blue arrows point to a curvilinear echogenic membrane within the gravid uterus. This is the amnion / amniotic membrane. The chorionic membrane is outside the amniotic membrane, out at the edge of the anechoic gestational sac and not visible.

Note how the yolk sac is always outside the amniotic sac.

Case Discussion

Single ultrasound image of a first trimester fetus to illustrate the amniotic membrane and its relationship to the fetus, yolk sac, and chorionic sac.

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Case information

rID: 37555
Published: 12th Jun 2015
Last edited: 26th Dec 2019
System: Obstetrics
Inclusion in quiz mode: Excluded
Institution: University of Pennsylvania