Many radiologists insist on it even when emergency physicians don't want it, it adds hours to the patient evaluation, and it dumps a large oral fluid load on a patient who may be having surgery, increasing the risk of aspiration, at least theoretically. All sorts of literature on this topic indicate that oral contrast adds little if anything to the evaluation when compared with noncontrast CTs, but this topic seems to be highly resistant to the evidence.
Concerning IV contrast:
IV contrast?! What possible reason could there be for using IV contrast in the patient with suspected appendicitis? I thought IV contrast was about the evaluation of solid organs such as liver, spleen, and kidneys. …. Using oral contrast is bad enough, but IV contrast is not without risks, particularly if there are issues regarding renal compromise.
He cited a couple of papers favoring non-contrast, the older of which I noted here.