Twin pregnancy has fascinated obstetric
providers for centuries, with
conjoined twins receiving attention
from the earliest medical recordings.
Conjoined twins are hypothesized to develop
secondary to the incomplete fission
of germinal disc after the 12th day of
embryogenesis.1 This incomplete germinal
disc fission would require that
conjoined twin pregnancies have monoamniotic
and monochorionic membranes.
1-4 Rare cases of conjoined twins
with diamniotic membranes have been
reported, which theoretically would be
improbable.3-8