Assessment of nuchal translucency thickness and the fetal anatomy in the first trimester of pregnancy by two- and three-dimensional ultrasonography: a pilot study

Abstract

To evaluate the use of three-dimensional ultrasonography (3D) as an alternative for examining fetal anatomy and nuchal translucency (NT) in the 1(st) trimester of pregnancy. Prospective study of 199 low risk pregnant women undergoing 1(st) trimester ultrasound scan for fetal anomalies. The NT and fetal anatomy were evaluated by three-dimensional (3D) ultrasonography after the standard two-dimensional (2D) examination. The gold standard in this study was the 2D ultrasonography. In some of the evaluated parameters the 3D method approaches the conventional 2D results. These parameters are the crown-rump length (CRL), the skull - brain anatomy (93.5%), the spine (85.4%), the upper (88.4%) and lower limbs (87.9%) and the examination of the fetal abdomen (98.5%). Some of the anatomic parameters under evaluation revealed a statistically significant difference in favor of the 2D examination. During the 3D examination the nasal bone was identified in 62.1% of the cases, the stomach in 85.9%, and the urinary bladder in 57.3% of the cases. The NT was assessed accurately in half of the cases compared to 2D examination. The 3D ultrasound is insufficient for the detailed fetal anatomy examination during the 1(st) trimester of pregnancy. Nevertheless, the method might be improved in order to be considered as a screening method.