Fig. 25. Transabdominal view of the pelvic area of an 8.5 month- old female fetus. The mammary gland appears as a hyperechoic triangular structure (4 MHz convex transducer).
when the fetus assumes a ventrocaudal position within the mare’s pelvis. In anterior presentation, the fetal hindquarters can be visualized transrec- tally up to 5 months gestation according to fetal size and location within the uterus. Rotation of the fe- tus over the long and short axis is commonly ob- served up to 8 months of pregnancy, and frequent changes of presentation occur around 5 to 6 months. At this time, repeating the exam 5 to 10 min later may find the fetus in a more advantageous position for diagnosis. A transabdominal approach is usu- ally necessary for gender determination over 5 months of gestation, when the fetus lies in anterior presentation. Good knowledge of fetal anatomy and rapid iden- tification of fetal parts are essential for ease of diag-
Fig. 27. Transabdominal view of the pelvic area of an 6.5 month- old female fetus. The mammary gland looks like a trapezoidal shaped structure and the nipples emerge as hyperechoic projec- tions of its ventral border (4 MHz convex transducer).
nosis. Diagnosis in advanced gestation should be based on at least three identified parameters. The time required to conduct a diagnostic examination is 1 to 5 min for the experienced examiner. Variabil- ity depends on the difficulty encountered in visual- izing the area of diagnostic interest, and a very active fetus generally makes a poor candidate for a rapid diagnosis. Video recording of scans provides opportunities for further studies and detailed evaluations. Finally, proper identification of the mare at the
time of examination and the provision of a signed certificate of fetal gender diagnosis should be an integral part of the service offered.
Fig. 26. Transabdominal view of the pelvic area of an 198 day- old female fetus, showing the mammary gland and the perineum (4 MHz convex transducer).
280 2014 Vol. 60 AAEP PROCEEDINGS
Fig. 28. Transabdominal view of the pelvic area of a 6 month-old female fetus showing the mammary gland and one nipple (4 MHz convex transducer).
