ABSTRACT
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Nausea is a subjective awareness of an impending urge to vomit. It is always unpleasant and can either precede vomiting or occur on its own. Patients use terms, such as “sick to the stomach” or “queasy,” when describing this symptom. Vomiting or emesis consists of rapid, retrograde, forceful ejection of gastric contents through the mouth. Repetitive contraction of abdominal wall muscles, termed retching, generates the pressure gradient necessary for the retrograde evacuation of stomach contents. Retching can occur without vomiting and, therefore, without evacuation of gastric contents. Vomiting can occur without preceding nausea in certain situations.1
