Chapter 131: Vomiting, Diarrhea, and Dehydration in Infants and Children

INTRODUCTION

Acute viral gastroenteritis is the most common cause of vomiting and diarrhea in children and continues to account for over 500,000 deaths globally each year in children <5 years old.¹ Transmission of GI infections can be reduced by attention to good hand washing, which can reduce the incidence of diarrheal disease by approximately 30% in both high- and low-income countries.² The provision of alcohol-based hand sanitizer and educational materials can reduce GI illnesses in child care centers,³ and a multifactorial intervention including hand sanitizer and surface disinfection similarly reduces illness due to enteric pathogens in elementary school students.⁴

Rotavirus previously accounted for the majority of severe cases and contributed significantly to hospitalizations in developed countries. However, the introduction of two live oral rotavirus vaccines, marketed as RotaTeq® and Rotarix®, for use in the United States and numerous other countries has resulted in an approximately 80% reduction in rotavirus-related hospitalizations and ED visits for rotavirus among immunized children.^5,6 Although a prospective postlicensure study of more than 200,000 doses identified an increase in the rate of intussusception after vaccination (attributable risk ~5.3 per 100,000 infants vaccinated), the increased risk must be weighed against the benefits of preventing rotavirus-associated illness.⁷ The reduction in rotavirus’s burden of disease along with the improved ability to identify norovirus has led to a realization that norovirus is now the pathogen responsible for the greatest burden of medically attended cases of gastroenteritis.⁸

Although the clinical diagnosis of gastroenteritis requires the presence of diarrhea, many infants present with isolated vomiting. This chapter focuses on one of the most frequent and important causes of vomiting and diarrhea in children, gastroenteritis, and will also review other important causes of these symptoms.

VOMITING

Vomiting is the forceful act of expelling gastric contents through the mouth. It 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 CNS 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 131-1). Bilious or bloody vomitus, hematochezia, or significant abdominal pain should trigger concerns of a disease process other than simple viral gastroenteritis or a potential complication of viral gastroenteritis (Tables 131-2 and 131-3).