Sonograms at 5–6 weeks of gestational age depict the embryo as a focal thickening at the periphery of the yolk sac—an appearance referred to as “diamond ring” sign (Fig. 1) [1]. The yolk sac represents the “ring” and the embryo represents the “diamond” in this earliest sign of embryonic development [2, 3].
Watch Dr. Anne Marie Valente present the last year's highlights in pediatric and congenital heart disease in the official ACC.24 Year in Review session.