Reece E A, Scioscia A L, Pinter E, Hobbins J C, Green J, Mahoney M J, Naftolin F
Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, CT 06510.
Am J Obstet Gynecol. 1988 Nov;159(5):1191-4. doi: 10.1016/0002-9378(88)90445-0.
Ultrasonographic examinations were conducted between 6 and 12 weeks' gestation in 77 first-trimester pregnancies with normal fetal outcome. Each examination consisted of measurements of the secondary yolk sac diameter and the fetal crown-rump length. The yolk sac was seen in all cases, and whereas its measurements demonstrated wide biologic variability, it correlated weakly (R2 = 0.39) with gestational age as confirmed by crown-rump length measurements. Growth of the yolk sac diameter, although slight, assumed a curvilinear relationship with gestational age. Such a growth profile is best described by a second-degree polynomial regression equation. The yolk sac performs important functions for embryonic development during organogenesis and the remnant of the secondary yolk sac seen on ultrasonography is often considered to be a potential predictor of fetal outcome. Our findings indicate that the size of this remnant in pregnancies with normal karyotypes and normal fetal outcomes is extremely variable. Additionally, the yolk sac size in patients with karyotypic abnormalities and spontaneous abortion were equally variable and almost all were within the normal range. In light of these findings, the secondary yolk sac size does not appear to be a sensitive predictor of embryonic integrity and pregnancy outcome.
对77例孕早期胎儿结局正常的妊娠进行了妊娠6至12周的超声检查。每次检查都包括测量次级卵黄囊直径和胎儿头臀长度。所有病例均可见卵黄囊，尽管其测量显示出较大的生物学变异性，但与通过头臀长度测量确定的孕周呈弱相关（R2 = 0.39）。卵黄囊直径的增长虽然轻微，但与孕周呈曲线关系。这种生长模式最好用二次多项式回归方程来描述。卵黄囊在器官发生过程中对胚胎发育发挥着重要作用，超声检查所见的次级卵黄囊残余物通常被认为是胎儿结局的潜在预测指标。我们的研究结果表明，核型正常且胎儿结局正常的妊娠中，这种残余物的大小变化极大。此外，核型异常和自然流产患者的卵黄囊大小同样变化不定，几乎所有都在正常范围内。鉴于这些发现，次级卵黄囊大小似乎不是胚胎完整性和妊娠结局的敏感预测指标。
