Departamento de Ginecología y Obstetricia, Hospital “Guillermo Grant Benavente”, and Departamento de Ginecología y Obstetricia, Facultad de Medicina, Universidad de Concepción, Concepción Chile.

This patient 1s a 32-year-old G1P0. This image was found during a routine term examination of a non-complicated pregnancy. Next to the transverse view of the fetal head, we observe a small sac with a thin membrane. The sac contains a small amount of tissue connected to the membrane by a thin pedicle. As the sac was attached to the placenta, near the cord"s insertion, we thought this represented a Vanishing Twin.

Detail of the placenta just after delivery. The sac is close to the cord"s insertion. It was covered by the other gestation"s amnion, which was removed before opening the sac.

When we opened the sac, a small amount of diluted bloody liquid poured slowly. Inside it we observed unidentifiable tissue which is showed in this image.

The placental biopsy confirmed our diagnosis of monochorionic-diamniotic pregnancy with a vanishing twin.