Ultrasound in the first trimester of pregnancy

28Citations
Citations of this article
5Readers
Mendeley users who have this article in their library.

Abstract

High-resolution sonography, including transvesical and endovaginal techniques, has resulted in enhanced visualization of embryonic and extraembryonic structures. With endovaginal sonography, the gestational sac may be seen within the decidua at about 4.5 weeks menstrual age. The yolk sac is the first structure to be seen within the gestational sac, and confirms the presence of a gestational sac rather than a decidual cast. The embryo is identified by endovaginal sonography early in the 6th week, and cardiac activity is routinely identified by a crown-rump length of 3 to 5 mm. On endovaginal sonography, absent cardiac activity in an embryo having a crown-rump length of greater than 3 to 5 mm indicates embryonic death. With endovaginal scanning, a gestational sac of greater than 8 mm without a yolk sac, or greater than 16 mm without an embryo, also indicates a nonviable pregnancy. Routine sonography primarily to assess the menstrual age should be performed in the second trimester, when added clinically relevant information may be obtained. Although it is possible to diagnose some anomalies in the first trimester, most remain second trimester sonographic diagnoses.

Cite

CITATION STYLE

APA

Levi, C. S., Lyons, E. A., & Lindsay, D. J. (1990). Ultrasound in the first trimester of pregnancy. Radiologic Clinics of North America. https://doi.org/10.1097/00013644-199301120-00001

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free