Vomiting is a common chief complaint for hospitalized pediatric patients. It is more often a symptom than a diagnosis and can be a presenting sign of illness in nearly every organ system. Investigation into the etiology of vomiting can help prevent metabolic-, nutritional-, and trauma-related complications as well as diagnose potentially life-threatening but treatable conditions.

PATHOPHYSIOLOGY

Vomiting is a highly coordinated, centrally mediated reflex. It occurs when the contents of the stomach are forcefully expelled out of the mouth. Descent of the diaphragm and constriction of abdominal musculature occurs simultaneously with the relaxation of the gastric cardia, forcing the contents of the stomach retrograde into the esophagus.

The vomiting centers of the brain, which reside in the reticular formation of the medulla, receive sensory input from a number of sources that trigger vomiting. These include afferent signals from the gastrointestinal (GI) tract arising from the vagus nerve and other sympathetic nerves, afferent signals from outside the GI tract originating from organs located in the thorax and abdomen, as well as sensory input received from the vestibular nucleus. Additionally, the chemoreceptor zone in the brainstem detects chemical abnormalities in the body, such as uremia or ketoacidosis. In the setting of cerebral trauma, extramedullary centers in the brain receive afferent signals as a result of signals from other areas of the brain. By understanding the pathophysiology of vomiting, one can appreciate that vomiting can be a manifestation of disease not only in the GI tract but in multiple organ systems.

A thorough history should be conducted in all children presenting with vomiting. The examiner can be guided by a few key elements of the history. What is the age of the patient? What is the character of the emesis? Bilious or nonbilious? Bloody or nonbloody? What is the nature of the emesis? Is it projectile? What was the onset? What is the timing? Is it associated with eating? Does it only occur in the morning? Are the vomiting episodes cyclical in nature? How have the symptoms progressed? Are there associated complaints within the GI tract? Are there associated systemic signs and symptoms such as fever or weight loss? Additionally, completing a comprehensive review of systems is a helpful adjunct in guiding the examiner toward an appropriate workup and ultimately in yielding a diagnosis.

The physical examination in the evaluation of the vomiting child begins with an overall assessment. Is the patient ill or toxic appearing? Next, a careful review of the vital signs with attention to age-appropriate normal ranges can help to guide the assessment of hydration status, acuity of the illness, and overall cardiovascular stability. A complete head-to-toe physical examination must be performed including a careful examination of the abdomen to determine presence of abdominal pain and distension. Assessing the overall patient and doing a thorough examination will help the examiner to narrow a very broad differential diagnosis for what is a common and often nonspecific presenting sign and symptom.

It is helpful to think through the differential diagnosis of vomiting in terms of gastrointestinal versus non-gastrointestinal pathologies as well as by age of the patient^1-3. (Tables 38-1,38-2,38-3,38-4).