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

AIM: 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. METHOD: 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. RESULTS: 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. CONCLUSION: 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.

First trimester 3D volumetry. Association of the gestational volumes with the birth weight.

OBJECTIVE: To evaluate the three dimensional ultrasound (3D) in the volume assessment of the gestational contents during the 1st trimester of pregnancy. Our aim was to correlate the embryo, gestational sac, and placenta volume with the birth weight. To monitor the increase of these volumes according to the gestational age. METHOD: Prospective study of 199 singleton low risk pregnant women undergoing the 1st trimester ultrasound for fetal anomalies. In these women, gestational volumetry was performed and it was compared with the crown-rump length (CRL). Regression models were computed in order to analyze the dependence of birth weight with the volumes. RESULTS: The embryo volume reveals the strongest association with the birth weight at delivery (ß = 0.24), followed by the CRL (ß = 0.20) and the gestational sac volume (ß = 0.20). The placenta volume appears the weakest association with fetal weight at delivery (ß = 0.16). All volumes increased significantly from 11(+0)-11(+6) to 13(+0)-13(+6) weeks of gestation (p < 0.001). Ten cubic millimeter increase in embryo volume corresponds to a mean birth weight increase of 75 g, while 1 mm increase in the CRL corresponds to a birth weight increase of 113 g. CONCLUSION: Our results provide evidence that the embryo volume during the first trimester of pregnancy correlates better with birth weight than the CRL. This might assist in the identification of the high risk pregnancies caring macrosomic and low birth weight fetuses.