Which of the following is true regarding chorionicity in multifetal pregnancy: (A) Monochorionic membranes should have four layers, (B) Dichorionic pregnancies are always dizygotic, (C) Monochorionic pregnancies are always dizygotic, (D) Chorionicity is accurately determined by first trimester ultrasound scan
Answer is D. Monochorionic pregnancies have dividing membrane that is 2 layer thick. Monozygous twins can be dichorionic as well.