Peptic ulcer disease Pancreatitis Peritonitis Paralytic ileus Crohn disease Neurologic Intracranial mass lesions (brain tumors, other) Cerebral edema Migraine Motion sickness Concussion Seizures Renal Obstructive uropathy Renal insufficiency/uremia Renal tubular acidosis Infectious Meningitis Urinary tract infection Hepatitis Upper respiratory infection (postnasal drip) Metabolic Diabetic ketoacidosis Reye syndrome Adrenal insufficiency Inborn error of metabolism (urea cycle or fatty acid oxidation defect; acute, intermittent porphyria) Toxins and drugs Aspirin Ipecac Digoxin Iron Lead (chronic) Respiratory (posttussive) Asthma exacerbation Infectious respiratory disease (pneumonia, bronchiolitis) Foreign body Other Pregnancy Cyclic vomiting 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 urgent radiologic workup For example, abdominal pain and bilious vomiting in an infant requires supine and upright plain films, as well as a limited upper GI series for evaluation of congenital obstructive anomalies such as malrotation A child with paroxysms of colicky abdominal pain and grossly bloody stools requires immediate ultrasound for rapid diagnosis of intussusception, or in clearcut cases should proceed directly to an air-contrast enema for both diagnosis and reduction of the intussusception Other situations require no imaging studies (e.g., a typical case of viral gastroenteritis) In many cases, cultures or serum chemical analyses are essential for making a diagnosis (e.g., meningitis, aspirin toxicity, urinary tract infection [UTI], pregnancy) or for guiding management (e.g., degree of metabolic derangement in severe dehydration, pyloric stenosis, diabetic ketoacidosis) For most straightforward, common illnesses (e.g., gastroenteritis, respiratory infections with posttussive emesis), laboratory investigation is unwarranted