What is the definition or description of: ultrasound of abdomen shows bull's eye?

Bull's eye by US: Ultrasound images can be very helpful to clinicians: they are pretty easy to obtain, not too expensive, very safe for patients and often lead to diagnosis. When the bowel telescopes on itself, aka intussuseption, it causes pain and obstruction and quickly becomes an emergency. With the walls of the bowel telescoped or folded onto themselves it looks like a target or bull's eye on ultrasound.

Intussusception: A bulls eye or target sign can be a sign of when bowel telescopes into itself causing an obstruction...........Intussusception.