Ultrasound Determination of Fetal Gender

CHAPTER 40 Ultrasound Determination of Fetal Gender

Fetal gender determination by real-time ultrasound evaluation has become a common reproductive management tool employed by both dairy and beef cow-calf operations. Other benefits of ultrasonography include early pregnancy diagnosis, diagnosis of fetal viability, twins and uterine pathology, and increased accuracy of ovarian structure identification.13 When fetal gender determination initially was utilized by beef cattle producers, the payback ratio was estimated to be at least 10:1 and sometimes as high as 100:1.4 It was thought at that time that the high profit margin probably was a result of the newness of the technology and that the procedure would remain profitable even after widespread acceptance. Those predictions have turned out to be accurate, because pregnant beef cows that are marketed with known-gendered fetuses routinely sell for $25 to $50 more per head than contemporaries with unknown fetal gender. Benefits of fetal gender determination for the dairy cow include the increased sale value of pregnant animals carrying heifers, ability to plan embryo transfer programs to fill bull contracts, cull decision information for marginal cows, and ability to predict replacement needs.

To accurately determine fetal gender, it is important that the practitioner have good-quality ultrasound equipment, an excellent understanding of fetal anatomy, and thorough training in reproductive ultrasonography. It also is important for practitioners to recognize the limitations of their ability, and of the technology itself, to ensure producer adoption of fetal gender identification. The reported accuracy of fetal gender determination approaches 100%.5 Under conditions of low light and calm cattle, this accuracy can be realized. Nevertheless, occasionally, despite the practitioner’s best effort, the necessary view cannot be obtained and therefore an accurate diagnosis cannot be made. In such instances it is imperative that the practitioner refrain from guessing; the producer should be informed of the limitations, and the examination be should be repeated in a few days. With experience, nondiagnostic examinations will occur with decreasing frequency.


A number of the ultrasound units available for purchase are more than adequate to identify fetal gender in cattle. Key areas of consideration in purchasing a scanner are image quality, portability, service, and power source.

Image quality is determined by a complex set of factors. An ultrasound unit has two basic parts, both of which affect image quality: the transducer and the console.


The number of elements of piezoelectric crystals in the transducer and the frequency of their vibration influence image quality. The number of crystals (or elements) in the transducer will be greater than 80 in most good machines. The frequency of vibration of the piezoelectric crystals is measured in megahertz (MHz). Transducers for bovine use commonly are available in frequencies of 3.5 MHz, 5 MHz, or 7.5 MHz. Lower-frequency transducers provide more depth of penetration but decreased resolution, so they are unsuitable for reproductive examinations. Higher-frequency transducers provide the best resolution but limit the depth of penetration, which may make scanning larger fetuses difficult. The standard transducer used in bovine reproductive ultrasonography has been the 5-MHz linear transducer, which we prefer in our practice. Some practitioners, however, prefer the increased resolution provided by the 7.5-MHz transducer.

Transducers are available in different shapes: linear, curvilinear, or sector. This designation refers to how the piezoelectric crystals are arranged in the transducer. As the name implies, the linear transducers have the crystals arranged in the head of the transducer in a linear fashion. The curvilinear transducer has a bend in the linear arrangement, and the sector scanner has a single crystal that oscillates, providing a wedge-shaped image. The sector and curvilinear scanners are awkward for routine rectal examinations. At this time, almost all transducers currently available for bovine ultrasonography are linear.

Other Components and Considerations

Sep 3, 2016 | Posted by in SUGERY, ORTHOPEDICS & ANESTHESIA | Comments Off on Ultrasound Determination of Fetal Gender

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