A 16 year old boy presents to the clinic with vomiting a moderate amount for 6 hours.  He has vomited 3 times, it is clear in colour and not projectile. He does not have any reported abdominal pain. He has voided 3 times today and has had one normal bowel movement. Earlier this morning he was playing hockey and was struck by another player. There was no reported loss of consciousness. He sustained no obvious injuries.

Physical Examination: He looks well.  Abdomen is soft. On auscultation, bowel sounds are normal. On palpation it is non-tender and there are no masses or organomegaly. The remainder of the physical examination is normal.