Ultrasound diagnosis of fetal abnormalities in multiple pregnancy.

Over a period of four years, 41 cases of abnormal multiple pregnancies were diagnosed successfully by ultrasound. These include several rare combinations of abnormalities. The most frequent was a normal pregnancy and a synchronous blighted ovum. Others were twin blighted ova, blighted ovum and missed abortion, missed abortion in both gestational sacs, two embryonic echoes with the development of only one baby, normal fetus and an anencephalic twin, normal fetus and fetus papyraceous, and triplets with two fetuses papyraceous. The results suggest that one or more gestational sacs may be resorbed during pregnancy without any adverse effect on the coexisting normal fetus. From a practical point of view, it is important to be aware of these possibilities before giving the final diagnosis of multiple pregnancy to the patient. The more diagnostic ultrasound is used in obstetrics, the more rare abnormalities associated with multiple pregnancies will be revealed.