Objective: To determine whether real-time three-dimensional (3D) ultrasound with Live xPlane imaging, which enables the simultaneous display of two real-time highquality image planes, can assist both operators certified by The Fetal Medicine Foundation (FMF) and non-FMFcertified operators in acquiring a true midsagittal plane in the first trimester. Methods: Eight operators, four of them FMF certified (FMF group) and the other four not (non-FMF group), were asked to acquire a fetal image that they believed to represent the true midsagittal plane using real-time 3D ultrasound with Live xPlane imaging as guidance. Each operator was asked to obtain such an image five times from each of five patients. A total of 200 images from 40 patients were obtained and stored for subsequent analysis. All pregnancies were between 11 + 0 and 13 + 6 weeks of gestation. The angle between the falx cerebri and vertical axis (angle of deviation) was then measured by a single operator. A true midsagittal section was defined as an angle of deviation equal to 0°. The angle of deviation and the time taken to acquire each image were compared between FMF and non-FMF groups. Results: The median angle of deviation for each operator ranged from 1.2° to 3.4°. There was no significant difference in this angle between those who were FMF certified and those who were not (2.0° vs. 2.2°, P = 0.463). The interquartile range of the angle of deviation was also similar between the FMF- and non-FMFcertified operators. Although the time taken for image acquisition was longer among the non-FMF-certified operators (median, 45.5s vs. 32.0s), this difference did not reach statistical significance (P = 0.107). Conclusion: Live xPlane imaging can provide a tool to assist the acquisition of a true midsagittal plane and to determine how true a 'midsagittal' plane really is. Copyright © 2010 ISUOG.