Are the first trimester volumetric measurements with two dimensional ultrasonography satisfactory?

Abstract

Objectives: Aim was to examine volumetric measurement of first trimester structures with two-dimensional ultrasonography (2D US) and evaluate necessity of three-dimensional (3D) volume measurements instead of 2D during first trimester. Methods: Using 2D transvaginal ultrasound imaging, the crown rump length (CRL), yolk sac (YS) and gestational sac (GS) diameters were recorded in 176 women with gestational age <11 weeks. Volume measurements were done by using a simplified formula for the volume of a prolate ellipsoid: V = 0.523 × length × height × width. Results: The mean CRL value was 19.6 ± 8.8 mm. The mean YS, GS and embrionic volume (EV) varied from 0.02–0.13, 5.5–37.72, 0.024–3.31 cm³ between 6⁺⁶ and 10⁺⁶ weeks, respectively. There was moderate positive correlation between EV versus GS volume and YS volume versus EV.Conclusions: 2D US still can provide adequate information in volumetric examination of regular shaped objects. But 3D US is useful in volumetric measurements of irregular shaped structures and for screening of fetal abnormalities.

Keywords::

• Embrio
• first trimester
• gestational sac
• pregnancy
• ultrasonography
• volume
• yolk sac

Declaration of Interest: The authors report no conflict of interest.