CHORIONICITY

Chorionicity is the most important determinant of pregnancy outcome in multiple pregnancies.

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

Video Clip of Split Membrane