Behavior of the Embryo

JOURNAL TITLE: Donald School Journal of Ultrasound in Obstetrics and Gynecology

1. Mohamed AM AboEllail
2. Nobuhiro Mori
3. Megumi Ito
4. Uiko Hanaoka
Publishing Year
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    Background: There have been only a few studies on conventional four-dimensional (4D) ultrasound assessment of embryonic movements early in the first trimester of pregnancy. With the latest 4D ultrasound, the frame rate in clinical examinations is around 7–20 frames per second depending on the size of the region of interest and number of lines employed using a transvaginal probe at 5–8 weeks of gestation. Moreover, HDlive with its adjustable light source and skin-like colors gives the embryo a natural and anatomically realistic appearance. Findings: At 5 weeks of gestation, a small dot-like embryo adjacent to the yolk sac can be noted as a round to oval structure. At 6 weeks of gestation, the embryo is a solid, comma-shaped structure adjacent to the yolk sac, but embryonic movements cannot be identified at this age. At 7 weeks of gestation, embryonic limb movements and a changing body direction can be noted. At 8 weeks of gestation, various types of movements, such as bending of the wrist, lower limb, upper and lower limb, twisting, startle, and general movements, can be recognized. Conclusion: New embryonic behavioral functions will be identified early in the first trimester of pregnancy using 4D ultrasound. Studies on embryonic behavior will help elucidate the functioning of the embryonic central nervous system, and help shed light on new areas of embryonic development.

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