3-DIMENSIONAL ULTRASONOGRAPHIC VISUALIZATION OF MULTIPLE PREGNANCY

Our purpose was to describe interrelationships and contacts between tw ins in utero by use of three-dimensional ultrasonography with a specia lly developed abdominal three-dimensional transducer. Thirteen twin pr egnancies (3 monochorionic and 10 dichorionic pairs) and one triplet p regnancy (trichorionic triplet) from 9 to 36 weeks of gestation were s tudied with a specially developed abdominal three-dimensional transduc er(3.5 MHz). This imaging system can provide conventional two-dimensio nal ultrasonography images and can also generate within seconds high-q uality three-dimensional images in the surface and transparent mode wi th no need for an external workstation. Interrelationships and contact s between twins or triplets are described. Various types of contacts ( head/body/arm/leg) and interrelationships were clearly visualized. Cro wding of in utero twin fetuses increased with advancing gestation. Som e times two placentas and dividing membrane were beautifully depicted. In one tripler pregnancy, the interrelationships among 3 fetuses and dividing membranes were easily recognized. Three-dimensional ultrasono graphy provides a novel means of visualizing multiple pregnancies in u tero. These results suggest that: three-dimensional ultrasonography ha s the potential to be a supplement to two-dimensional ultrasonography and would be useful in evaluating the interhuman contacts and crowding s of twin and triplet fetuses in utero.