Application of transvaginal and abdominal three‐dimensional ultrasound for the detection or exclusion of malformations of the fetal face

Abstract

In a total of 618 pregnant women between 9 and 37 weeks' gestation, the fetal face was evaluated by two‐dimensional and three‐dimensional ultrasound imaging as part of a level III screening evaluation for fetal anomalies. A three‐dimensional endovaginal probe (5 MHz) was used for examinations at between 9 and 15 weeks, and an abdominal three‐dimensional probe (3.5 MHz) was used after 15 weeks. Three different three‐dimensional image display modes were employed: (1) the orthogonal display; (2) the surface display; and (3) the transparent display. When we studied the three‐dimensional orthogonal displays in 125 cases evaluated by abdominal ultrasound, we found that the facial profile shown in the two‐dimensional image represented the true mid‐sagittal profile in only 69.6% of cases. In the remaining 30.4%, the profile view deviated from a true mid‐sagittal section by up to 20° in one or two planes. In a total of 25 facial anomalies detected by abdominal ultrasound, 20 were clearly demonstrated by both two‐dimensional and three‐dimensional technology. In the remaining five cases, three‐dimensional ultrasound revealed or confirmed an additional defect or abnormality: a narrow cleft lip in an unfavorable position of the fetal face (n = 2), a unilateral orbital hypoplasia (n = 1), a cranial ossification defect (n = 1) and a flat profile in the presence of marked oligohydramnios (n = 1). When transvaginal scanning was used, there were cases in which a detailed surface image of the fetal face could be obtained as early as 9 weeks' gestation. Abdominal scanning routinely yielded high‐quality surface images by 20 weeks. Three‐dimensional ultrasound consistently displayed facial abnormalities with greater accuracy and clarity than conventional two‐dimensional imaging. This particularly applied to chromosomal aberrations and syndromes associated with subtle facial abnormalities requiring a detailed evaluation. Not only does three‐dimensional ultrasound help in appreciating the severity of a fetal defect, but it can also provide more convincing evidence of a normal fetus than conventional two‐dimensional sonograms. Copyright © 1997 International Society of Ultrasound in Obstetrics and Gynecology