Vomiting, Diarrhea, and Dehydration in Children

Acute viral gastroenteritis is the most common cause of vomiting and diarrhea in children, with a worldwide mortality rate of 1.5 million per year in children <5 years of age.1 The clinical diagnosis of gastroenteritis by definition requires the presence of diarrhea. However, many infants with viral gastroenteritis present with isolated diarrhea or isolated vomiting. This chapter focuses on the most important cause of vomiting and diarrhea in children, gastroenteritis, and will also review other important causes of these symptoms.

Vomiting is the forceful, coordinated act of expelling gastric contents through the mouth. It is is controlled by the vomiting center in the reticular formation of the medulla, and the chemoreceptor trigger zone underlying the floor of the fourth ventricle. Trigger areas that excite the central nervous system vomiting centers are found in the pharynx, cardiac vessels, peritoneum, bile ducts, and stomach. Vomiting results when the stomach relaxes, the gastric pylorus constricts, and the contractions of surrounding muscles cause expulsion of the gastric contents. Acute vomiting is usually caused by a self-limited viral illness. Nonetheless, serious diagnoses that need to be considered include infections, metabolic abnormalities, neurologic processes, acute surgical/GI diseases, or other major organ system dysfunction. The differential diagnosis of vomiting is age specific (Table 123-1).

Regurgitation is the reflux of stomach contents without forceful vomiting. In infants, it is often a sign of gastroesophageal reflux, which is physiologic in young infants and usually resolves ...