CASE REPORT
A 37-year-old woman, gravida 3, para 1,
who spontaneously conceived, presented
at 9 weeks of gestation for evaluation
of her twin pregnancy. Transvaginal
ultrasound showed a single
intrauterine gestational sac that contained
2 embryos, each of which was surrounded
by an amnion (Figure 1), confirming
monochorionic diamniotic
placentation. The embryos shared a
common yolk sac (Figure 2) and were
joined periumbilically. The patient’s history
included surgical correction of aortic
coarctation and subaortic stenosis.
Her first pregnancy was uncomplicated
and resulted in delivery of a healthy
child, who was later diagnosed with autism.
During her second pregnancy, dilation