aureole: A ring of bright echoes in a ring. A fine weak echo aura is present in the dark area of the uterus, which is a reflection of the amniotic membrane and can appear wavy. The fetal cranial cavity and eyelids are strong echo auras.Veterinary B Ultrasound
Acoustic shadow: The area of the anechoic shadow after the strong echo appears in the gas-filled intestinal cavity and the strong echo of the fetal bone. The latter's sound shadow is clear, and its appearance and enhancement can show the degree of ossification of the fetal bone.
Gas echo: echoes reflected by gas-bearing organs such as the intestines, such as clouds, followed by sound and shadow, but the edges are unclear, often found in the absence of pregnancy, can be used as a reference for the diagnosis of pregnancy.