cor triatriatum

https://sonoworld.com/fetus/page.aspx?id=3197

In this fetus, at 35 weeks, we observed a thick and linear echogenic structure in the right atrium protruding laterally from the lower third of the interatrial septum and mimicking a Cor triatriatum dexter ⁽¹⁾. It was located in the inferior wall of the right atrium and was continuous with the superior border of the orifice of the coronary sinus.

Figure 1, 2: Arrows demonstrated the Prominent Eustachian valve.