Scope of the problem

Vomiting is a common presenting complaint to the emergency department (ED), accounting for nearly 2 million annual visits. It has no age or gender predilection, and has many etiologies. The most common causes of vomiting are acute gastroenteritis, febrile systemic illness, and drug-related effects. The emergency physician's main responsibility is differentiating the emergent and life-threatening causes of vomiting from those caused by more benign entities. The remainder of ED management is targeted toward symptom alleviation and rehydration.

Pathophysiology

Vomiting is induced by physical stimulation of the back of the throat (gag reflex), mucosal irritation of the upper digestive tract, stimulation of the vomiting center in the medulla oblongata, stimulation by biochemical emetic stimuli on the chemoreceptor trigger zone in the area postrema, or by severe emotion. Nausea frequently precedes vomiting and is marked by reduced gastric tone and peristalsis. Regurgitation, by contrast, is the passive retrograde movement of esophageal contents into the mouth, as in gastroesophageal reflux.

True vomiting refers to the rapid ejection of gastric contents. The abdominal muscles rapidly contract, while the cardia of the stomach, esophagus, and throat remain open with the glottis closed. Copious salivation usually precedes vomiting, and serves to lubricate the digestive tract and dilute the gastric acid. Repeated contractions of the abdominal muscles against a relaxed stomach produce retching. The repetitive abdominal contractions build up a pressure gradient in the stomach prior to vomiting. This allows gastric contents to move to the upper portion of the stomach.