DIFFERENCES BETWEEN DICHORIONIC

AND MONOCHORIONIC TWINS

	Dichorionic	Monochorionic
Inter twin membrane	Thicker(>2mm) More echogenic	Thinner(<2mm) Less echogenic
Twin peak sign / T-sign	Present	Absent
Placenta	2 placentas:   - separate   - fused	Single placenta
Sex of fetus	Same or different	Always the same
Split membrane sign	Present	Absent

Split membrane sign
Dichorionic Diamniotic Twins – 6+1 wks GA
Monochorionic Diamniotic Twins (10 wks): Two yolks sacs. Thin inter-twin membrane. Placentas not yet discernable as separate
Monochorionic monoamniotic twuns – 3D

Monochorionic Diamniotic Twins- Only 1 yolk sac seen Monochorionic Diamniotic Twins - Membranes Monochorionic Diamniotic Twins - 2  yolk sacs seen Dichorionic Diamniotic Twins Split Membrane sign of Dichorionic twins