<prompt> Twin peak sign seen inMonochorionic MonoamnioticMonochorionic DiamnioticDichorionic DiamnioticDichorionic Monoamniotic  <response>: Twin peak or lambda sign it is characterized of dichorionic pregnancies and is due to the chorionic tissue between the two layers of the intewin membrane at the placental origin . twin peak appears as a triangle with base at chorionic surface and apex in intewin membrane. 