Goldstein S R
New York University School of Medicine, NY 10016.
Am J Obstet Gynecol. 1991 Sep;165(3):497-501. doi: 10.1016/0002-9378(91)90274-u.
New endovaginal probes will result in many investigators reexamining the crown-rump length data first generated with static arm and abdominal real-time scanners. As new tables are produced, only through better understanding of the anatomy of early embryos can we realize what we are actually seeing and measuring (or at least attempting to measure). Furthermore, as we try to correlate early embryonic size with gestational age, we realize that the crown-rump measurement is not applicable in principle or in nomenclature when the embryo is less than 18 mm long. When first seen, the embryo is relatively straight; a measurement of its size is best described as "greatest length." As the embryo curves into a C-shaped, tadpolelike structure, the greatest measurement along the long axis is actually a neck-rump measurement. Further unfolding of the head and regression of the tail finally allow an accurate crown-rump measurement (at about 18 mm) as we have used it for almost two decades. Early embryonic stages and characteristics are reviewed and methods of measurement of early embryonic size are explained.
新型阴道探头将促使许多研究人员重新审视最初使用静态臂式和腹部实时扫描仪生成的头臀长度数据。随着新表格的产生，只有通过更好地了解早期胚胎的解剖结构，我们才能明白我们实际看到和测量的（或至少是试图测量的）是什么。此外，当我们试图将早期胚胎大小与孕周相关联时，我们意识到当胚胎长度小于18毫米时，头臀测量在原则或命名上都不适用。最初观察到胚胎时，它相对较直；此时对其大小的测量最好描述为“最大长度”。当胚胎弯曲成C形、蝌蚪状结构时，沿长轴的最大测量实际上是颈臀测量。随着头部进一步展开和尾部退化，最终才能够进行准确的头臀测量（约18毫米），而我们已经使用这种测量方法近二十年了。本文回顾了早期胚胎阶段和特征，并解释了早期胚胎大小的测量方法。
