1. Multifetal pregnancy. A: TAS of normal 7-week diamniotic, dichorionic twin IUP. B: TVS of demised embryo (+'s) adjacent to living twin at 7 weeks. C: TAS of "vanished" twin within an empty sac adjacent to a living embryo with an intact sac (between +'s) D: Diamniotic/dichorionic twin gestation showing thick interface between gestational sacs. E: Triplet intrauterine pregnancy showing thick membrane between sacs most likely representing trichorionic. F: Twin IUP with hypoechoic area to the left of the sacs most likely representing either unobliterated lumen or small retrochorionic hemorrhage. G: Intrauterine gestation with small sac, probably remnant of a second sac that contained an embryo. This most likely represents twin pregnancy with embryonic demise of one twin. H: Twin gestation with thin membrane most likely representing monoamniotic. The upper twin was adjacent to the choriodecidua and had a very short umbilical cord, suggesting the possibility of a body stalk anomaly.
Source: TRANSVAGINAL SONOGRAPHY OF EARLY INTRAUTERINE PREGNANCY, Sonography in Obstetrics and Gynecology: Principles & Practice, 7e
Citation: Fleischer AC, Toy EC, Lee W, Manning FA, Romero RJ. Sonography in Obstetrics and Gynecology: Principles & Practice, 7e; 2014 Available at: Accessed: December 31, 2017
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