to assess hydration of infants presenting with gastroenteritis and to ensure adequate oral intake, particularly in those infants who also have diarrhea as this age group is at much higher risk of dehydration than older children Vomiting in infants may also be caused by pathology of organ systems outside the digestive system and should be considered in the infant presenting with vomiting These include infectious, neurologic, renal, and metabolic causes Infections outside the GI tract can present with vomiting in infants One of the most common infections to cause vomiting outside of the GI tract is UTI UTIs are a common source of fever in children, particularly in infants Clinical symptoms are often nonspecific in infants, but may include vomiting in as many as one-third of infants with UTI, poor feeding, or malodorous urine Infants with pneumonia may also present with fever and vomiting, along with tachypnea, cough, or increased work of breathing Any respiratory illness causing cough, including bronchiolitis, pneumonia, and pertussis, can be associated with posttussive emesis in this age group Neurologic causes of vomiting in infants include CNS infections such as meningitis, hydrocephalus, intracranial mass, and intracranial hemorrhage Signs and symptoms of increased ICP in infants may include vomiting in addition to lethargy, irritability, bulging anterior fontanel, seizures, or focal neurologic findings Other causes of vomiting outside the GI tract include renal and metabolic causes Infants with renal tubular acidosis (RTA) may present with vomiting, growth failure, and recurrent episodes of dehydration Children with renal failure may also present with vomiting Vomiting can be an early symptom of many of the inborn errors of metabolism, including urea cycle disorders and organic acidemias Infants with inborn errors of metabolism may present with vomiting, lethargy, and poor feeding, and this diagnosis should be kept in the differential diagnosis of infants presenting with recurrent vomiting Older Child In the older child, several of the obstructive causes of vomiting can continue to occur, although less commonly than in infancy Children in this age group may present with malrotation and volvulus, intussusception, incarcerated hernia, or enteric duplication cysts Children with a history of abdominal surgery may present with bowel obstruction caused by adhesions Signs of obstruction in this age group include vomiting (particularly bilious), abdominal distention, and pain Nonobstructive causes of vomiting continue to be more common than obstructive causes of vomiting in older children GI causes such as appendicitis, peptic ulcer disease, and gastroenteritis can lead to vomiting, as well as several