History: 25 year old female with acute lower abdominal pain, nausea and vomiting.
Given the history, this is essentially diagnostic of appendicitis. Take a look again at the image. The appendix has a target appearance, which also aids in the diagnosis. The target appearance is caused by edema within the various layers of the appendix wall.
The appendix is very difficult to localize in most attempts of abdominal ultrasound, and many times patients go on to CT for definitive diagnosis. A nice overview of the radiology of appendicitis can be found here.