Pediatric Abdominal Ultrasound

After a long shift in the adult ED, jam packed with patients presenting with abdominal pain, your looking forward to a brand new day in the Peds ED.  Your first patient, however, gives you PTSD-like flashbacks to the previous days shift.  

Alice is a 8 year old girl who developed abdominal pain last night.  Her parents thought that she would be okay waiting until morning, that the pain would pass in the night.  On waking this morning, however, the pain was still there.  Sharp pain located in the right side of her abdomen was initially intermittent but has since became constant.  Her parents say that she didn't seem to sleep well last night, didn't eat breakfast this morning, and then, shortly before coming into the ED, vomited several times.  On exam she has some generalized abdominal tenderness, worse in the right lower quadrant.  Her urinalysis is negative for signs of infection.  You order up an ultrasound of her abdomen to look for appendicitis and look for a resource to familiarize yourself with the normal findings on abdominal ultrasound.