Introduction: Conjoined twins occur in approximately 0.2:10,000 births; the obstetrician and sonographer only rarely examine them. In Western countries, discovery of conjoined twins is often made by the end of the first trimester; however, in the third world, conjoined twins are often discovered only at birth.
Objective: To evaluate how ultrasound techniques, when possibly available, may improve management and counseling when conjoined twins are confirmed.
Material and methods: The authors report two different cases of union of two equal twins with sole umbilical cord.
Results: The two cases presented with non contributive medical history and no prior teratogen exposure and an unfavorable prognosis. Early discovery of viable conjoined twins permits assessment of the best route of delivery and a planning for serial sonography and fast MRI to plan eventual separation surgery or fetus after-birth surviving possibilities.
Keywords: conjoined twins; ultrasound.