Multiple gestations: the importance of ultrasound.

The use of ultrasound in the diagnosis of twins, its role of determining chorionicity, the management of unique twin complications, the value of cervical length determination in twins, the use of ultrasound in screening for aneuploidy in multiples, and the intrapartum role of ultrasound in twin gestations have been reviewed. The availability of high-resolution ultrasound has significantly im-proved the management of multiple gestations.