Ultrasonography of the Human Yolk Sac
Static scanners gradually became to be widely used in obstetrics following a report of the detection of fetal echoes at 14 weeks of gestation (Donald et al. 1958). During the mid-1970s, growth parameters of the gestational sac and embryo as from 6 weeks of gestation were measured using gray scale static scanners; the clinical criteria for the examination of the pregnant patient and the differentiation of normal intrauterine pregnancy and missed abortion were established. In 1979 the first sonographic analysis of the human yolk sac between 7 and 11 weeks of gestation was reported (Mantoni and Pedersen 1979); clear images of the yolk sac were obtained in 19 out of 22 cases. At the time, the clinical relevance of these findings was limited to avoiding erroneous measurements of the crown-rump length, although we found at our center that a clear visualization of the yolk sac allowed us to reject inconsistent diagnosis of early neural tube defects.
KeywordsHeart Activity Full Bladder Viable Pregnancy Transvaginal Probe Embryonic Pole
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