TABLE 81.2 LIFE-THREATENING CAUSES OF VOMITING Newborn (birth to wks) Anatomic anomalies—esophageal stenosis/atresia; intestinal obstructions ( Table 81.1 ), especially malrotation and volvulus; Hirschsprung disease Other gastrointestinal (GI) causes Necrotizing enterocolitis Peritonitis Neurologic—kernicterus, mass lesions, hydrocephalus Renal—obstructive anomalies, uremia Infectious—sepsis, meningitis Metabolism—inborn errors, especially congenital adrenal hyperplasia Older infant (2 wks to 12 mo) Intestinal obstruction ( Table 81.1 ), especially pyloric stenosis, intussusception, incarcerated hernia, malrotation with volvulus Other GI causes, especially gastroenteritis (with dehydration) Neurologic—mass lesions, hydrocephalus Renal—obstruction, uremia Infectious—sepsis, meningitis, pertussis Metabolic—inborn errors of metabolism Toxins, drugs Older child (older than 12 mo) GI obstruction, especially intussusception ( Table 81.1 ) Other GI causes, especially appendicitis, peptic ulcer disease Neurologic—mass lesions Renal—uremia Infectious—meningitis, sepsis Metabolic—diabetic ketoacidosis, adrenal insufficiency, inborn errors of metabolism Toxins, drugs The diverse nature of causes for vomiting makes a routine laboratory or radiologic screen impossible The history and physical examination must guide the approach in individual patients Certain well-defined clinical pictures demand