[Prenatal ultrasonic diagnosis of a dicephalic fetus in the 18th week of pregnancy].

The authors report a case of conjoined twins (dicephalus) detected antenataly in the 18-th week of pregnancy by routine ultrasound screening. The pregnancy was terminated because this congenital malformatión is incompatible with extrauterin life. The embriopathological examination confirmed the prenatal diagnosis. The ultrasonographic criteria are discussed and the importance of early diagnosis is stressed.