What's already known about this topic?
- Spontaneous septostomy of the chorionic membrane in dichorionic diamniotic (DCDA) twin pregnancy is an extremely rare event with only a two reported cases, so far none with associated increased NT.
What does this study add?
- This case reports a spontaneous septostomy of the chorionic membrane associated with increased NT in the first trimester with favorable pregnancy outcome. Along with an overview on the previous cases, possible etiologies and the role of genetic counseling and invasive karyotyping are discussed.