Up or down? A randomized trial comparing image orientations during transvaginal ultrasound training

There is no international consensus on the orientation of transvaginal ultrasound images and no evidence exists to support the superiority of one image orientation over the other. The aim of this study was to compare learning curves and skills transfer in a group of novices randomized to top-down or bottom-up image orientation, and to determine whether individual preferences for image orientation affect learning and skills transfer.

60 senior medical students, with no prior ultrasound experience, were randomized to orient the image top-down or bottom-up during training on an ultrasound simulator until attaining expert levels of performance. Participants then completed a transfer test involving a systematic ultrasound examination on a physical mannequin using real ultrasound equipment. Performance was assessed during the transfer test by two independent raters using the objective structured assessment of ultrasound skills (OSAUS) score and a global rating score.

The bottom-up group reached the expert level with significantly fewer attempts than did the top-down group [median ± interquartile range: 4 ± 2 vs 5 ± 3] (U = 285.5, P = 0.014). The bottom-up group used less time to achieve the expert level (median ± interquartile range: 3 h 2 m ± 1 h 14 m vs 3 h 28 m ± 2 h 21 m) (U = 301.5, P = 0.029). The two groups performed similarly during the transfer test with respect to their OSAUS scores (top-down 56.7% vs bottom-up 53.2%, P = 0.13). The global rating scores were higher in the top-down group (top-down 57.1% vs bottom-up 50.0%, P = 0.02).

Orientation of the images bottom-up rather than top-down, led to a steeper learning curve, but had little or no impact on the subsequent transfer of skills.