[Gender determination in equine fetuses in early pregnancy using two- and three-dimensional ultrasound].

AIM

The aim of this study was to compare transrectal two-dimensional (2D) and three-dimensional (3D) ultrasound examination with regards to required time and accuracy of fetal sex determination in early pregnant mares.

MATERIALS AND METHODS

For this purpose 47 mares were examined transrectally once between days 58 and 115 of gestation. Initially, the fetal sex was determined by identifying the location of the genital tubercle (GT) or external genitalia using 2D-ultrasound. Subsequently, the ultrasound machine was switched to 3D-mode to obtain images for later computer-based evaluation.

RESULTS

The gestational period between days 58 and 79 of pregnancy was the most appropriate time for sex determination with 77 % (2D and first 3D evaluation) correct diagnoses. The accuracy of the sex determination could be increased by about 16 % by a second evaluation of the 3D-images in a minimum time interval of 2 weeks. For each mare the additional time needed to perform the 3D-examination and to assess the 3D-images was approximately 6-7 minutes.

CONCLUSION AND CLINICAL RELEVANCE

This study demonstrates that the accuracy of transrectal fetal gender determination is higher by using 3D-mode compared to the 2D-ultrasound. For experienced examiners however, 3D ultrasound technology does not offer any decisive advantages and is also more time-consuming.