1 What is the pathophysiology of vomiting?

True vomiting is the forceful elimination of gastrointestinal contents through the mouth or nose. Vomiting is caused by coordinated diaphragmatic and abdominal contractions in conjunction with pyloric constriction and gastroesophageal relaxation. This motor activity occurs in response to stimulation of the medullary “vomiting center” by impulses from a variety of anatomic locations. Sources of these impulses include the pelvic and abdominal viscera, the heart, the peritoneum, the labyrinth, and the “chemoreceptor trigger zone,” an area on the floor of the fourth ventricle that is sensitive to circulating drugs, toxins, and metabolic derangements.

2 What is the clinical difference between vomiting and “spitting up”?

It is important to differentiate vomiting from “spitting up” because the causes of spitting up are rarely serious while vomiting may indicate a potentially life-threatening condition. Spitting up is characterized by effortless regurgitation of stomach or esophageal contents and in most infants and children is due to gastroesophageal reflux or overfeeding. Vomiting, on the other hand, is forceful, may be accompanied by retching, and is frequently associated with autonomic symptoms, such as salivation, pallor, sweating, tachycardia, and mydriasis.

3 What is the differential diagnosis of vomiting in the pediatric patient?

Vomiting may be caused by abnormalities in a variety of organ systems. When preschool-aged patients report “vomicking,” they help us to remember the wide-ranging differential diagnosis with the following mnemonic:

Furnival RA: Vomiting. In Harwood-Nuss A, Linden CH, Luten RC, et al (eds): The Clinical Practice of Emergency Medicine, 2nd ed. Philadelphia, Lippincott-Raven, 1996, pp 1265–1267.

4 The differential diagnosis for vomiting depends on the age of the pediatric patient. What are the life-threatening causes of vomiting in the different pediatric age groups?

See Table 29-1.

Table 29-1 Life-Threatening Causes of Vomiting by Age

Age	Cause
Neonate	GI obstruction Congenital intestinal obstruction Atresias Malrotation with volvulus Renal Obstructive uropathy Uremia Trauma Shaken baby syndrome with subdural hematoma Abdominal trauma Metabolic Inborn metabolic errors Congenital adrenal hyperplasia Infectious Sepsis Meningitis Severe gastroenteritis Necrotizing enterocolitis Neurologic Hydrocephalus

Older infant/toddler GI obstruction

Renal

Trauma

Infectious

Neurologic

Toxic ingestions

Older child/adolescent

GI obstruction

Renal

Infectious

Metabolic

Neurologic

Toxic ingestions
Inflammatory

GI = gastrointestinal.

Burton BK: Inborn errors of metabolism in infancy: A guide to diagnosis. Pediatrics 102:E69, 1998.

Stevens M, Henretig FM: Vomiting. In Fleisher GR, Ludwig S, Henretig FM, et al (eds): Textbook of Pediatric Emergency Medicine, 5th ed. Baltimore, Williams & Wilkins, 2006, pp 682–683.

5 What are the most common causes of vomiting in the different pediatric age groups?

See Table 29-2.

Table 29-2 Common Causes of Vomiting by Age

Age	Causes
Neonates	GI GE reflux Congenital GI obstruction (intestinal atresias, malrotation) Milk-protein allergy Infectious Sepsis/meningitis

Older infant/toddler

GI

Infectious

Toxic ingestion Older child/adolescent

GI

Infectious

Metabolic

Toxic ingestion
Other

GE = gastroesophageal; GI = gastrointestinal.

Stevens M, Henretig FM: Vomiting. In Fleisher GR, Ludwig S, Henretig FM, et al (eds): Textbook of Pediatric Emergency Medicine, 5th ed. Baltimore, Williams & Wilkins, 2006, p 683.

6 What should be the first steps in evaluating the infant or child with vomiting?

In the stable child who does not require resuscitation, evaluation of the infant or child with vomiting should begin with a careful history and physical examination. There is little value in screening laboratory or radiologic tests in most infants and children who have uncomplicated gastroenteritis. The information gathered will help to identify any acute needs the child may have, quantify the degree of dehydration caused by the vomiting, and allow the clinician to focus the differential diagnosis.

7 What information should be obtained in the history of a child who is vomiting?

Useful historical information includes:

8 What clinical clues can be obtained from the appearance of the vomitus?

When obtaining a history from a patient with vomiting, details about the appearance of the vomitus can help pinpoint the location of the problem.

Appearance	Source/Cause
Undigested food	Esophageal lesion or reflux
Digested food, milk curds	Stomach, proximal to pylorus
Yellow-green, bilious	Obstruction distal to ampulla of Vater or retrograde peristalsis during retching causing gastroduodenal reflux
Feculent	Distal obstruction, colonic stasis
Blood	Lesion proximal to ligament of Treitz
Bright red blood	Esophagus or stomach above the cardia minimal contact of blood with gastric secretions
Brown, “coffee grounds”	Gastric bleeding or swallowed blood mixed with gastric secretions
Mucus	Upper respiratory tract, gastric mucous hypersecretion

Orenstein SR, Peters JM: Vomiting and regurgitation. In Kliegman RM, Greenbaum LA, Lye PS (eds): Practical Strategies in Pediatric Diagnosis and Therapy. Philadelphia, WB Saunders, 2004, pp 291–321.

Sadow KB, Atabaki SM, Johns CM, et al: Bilious emesis in the pediatric emergency department: Etiology and outcome. Clin Pediatr 41:475–479, 2002.

9 What information should be obtained during the physical examination of a child with vomiting?

The physical examination should initially focus on adequacy of perfusion and cardiovascular stability. Then, measures that indicate degree of dehydration should be assessed. The presence of two of the following four findings (dry mucous membranes, absent tears, abnormal lethargy or restlessness, and capillary refill time >2 seconds) are associated with at least 5% dehydration; the presence of three or more is associated with 5% dehydration or greater. The remainder of the examination should comprehensively assess the abdomen as well as the respiratory, cardiac, and neurologic systems.

Gorelick MH, Shaw KN, Murphy KO: Validity and reliability of clinical signs in the diagnosis of dehydration in children. Pediatrics 99:e6, 1997.

10 What laboratory tests are indicated in the child with vomiting?

Laboratory testing in the child with vomiting should be guided by the history and physical examination. In children with significant dehydration or those whose initial assessments suggest causes other than uncomplicated gastroenteritis, carefully selected laboratory tests can provide useful clues or confirm diagnoses (Table 29-3).

Table 29-3 Laboratory Testing in Pediatric Patients with Vomiting

Test

Diagnostic Utility

Serum electrolytes

Sodium Elevated in hypernatremic dehydration Decreased in hyponatremic dehydration, adrenal insufficiency Potassium Elevated in renal failure, adrenal insufficiency Decreased in pyloric stenosis Chloride Decreased in pyloric stenosis, bulimia Bicarbonate Elevated in significant or chronic vomiting (e.g., bulimia), pyloric stenosis Decreased in inborn metabolic errors, renal tubular acidosis, other causes of metabolic acidosis (sepsis, uremia, toxic ingestions, shock, acute gastroenteritis with dehydration) Glucose Elevated in diabetic ketoacidosis Decreased in inborn metabolic errors, starvation, toxic ingestion

Serum blood urea nitrogen/creatinine Elevated in dehydration, renal failure White blood count Elevated in serious bacterial infection Urinalysis Specific gravity: elevated in dehydration   Glucose with or without ketones: present in diabetes, diabetic ketoacidosis   Ketones: elevated in starvation, dehydration, inborn metabolic error
Red blood cells: renal calculi, nephritis, UTI
White blood cells: UTI Urine pregnancy test Pregnancy Amylase, lipase Elevated in pancreatitis Aminotransferases Elevated in hepatitis

UTI = urinary tract infection.

Liebelt EL: Clinical and laboratory evaluation and management of children with vomiting, diarrhea and dehydration. Curr Opin Pediatr 10:461–469, 1998.

Orenstein SR, Peters JM: Vomiting and regurgitation. In Kliegman RM, Greenbaum LA, Lye PS (eds): Practical Strategies in Pediatric Diagnosis and Therapy. Philadelphia, WB Saunders, 2004, pp 291–321.

11 When are radiographic tests indicated in the pediatric patient with vomiting?

Radiographic tests may help differentiate causes of vomiting that require surgical intervention from those that do not. Plain radiographs of the abdomen are an appropriate initial study in this clinical situation. A plain abdominal film together with an upright film (or cross-table lateral view in the nonambulatory patient) may demonstrate distended bowel loops or air-fluid levels consistent with obstruction. A plain radiograph may also demonstrate abnormal calcifications, such as renal or biliary stones or fecaliths. Free air may be observed on the upright/cross-table film in the case of hollow viscus perforation. Basilar infiltrates caused by lower-lobe pneumonias may be noted serendipitously on an abdominal film, although chest radiography would be the better diagnostic test for pulmonary pathology.

12 Which radiographic tests are most useful when further evaluating specific causes of vomiting that may require surgical intervention?

See Table 29-4.

Table 29-4 Radiographic Studies for Evaluating the Child with Vomiting

Clinical Concern	Radiographic Study of Choice
Appendicitis	Abdominal ultrasonography and/or abdominal CT with or without rectal contrast
Intussusception	Abdominal ultrasonography, contrast enema
Malrotation, intestinal atresias	Upper GI series
Pyloric stenosis	Abdominal ultrasound or upper GI series
Renal calculi	Abdominal CT without contrast
Ovarian or uterine pathology	Pelvic ultrasonography
Pancreatic pathology	Abdominal CT with IV and oral contrast
Duodenal hematoma/other intestinal pathology	Abdominal CT with IV and oral contrast
Abdominal mass	Abdominal CT with IV and oral contrast

CT = computed tomography; GI = gastrointestinal.

Heller RM, Hermanz-Schulman M: Applications of new imaging modalities to the evaluation of common pediatric conditions. J Pediatr 135:632–639, 1999.

13 What treatment is indicated for the infant or child with vomiting?

Treatment of the infant or child with vomiting is focused first on treating dehydration or maintaining adequate hydration and then on treating the specific cause of the vomiting, when indicated. Dehydration can be treated effectively by either rapid IV rehydration using isotonic crystalloid solution or by appropriately supervised oral rehydration with a suitable rehydration solution. Because most vomiting in children is self-limited or resolves when the underlying cause is treated, antiemetics are not routinely advised, except in specific clinical circumstances (e.g., vomiting from chemotherapy or in the cyclic vomiting syndrome). In children who require ED rehydration during an acute gastrointestinal illness associated with vomiting, randomized controlled trials have demonstrated reductions in emesis and the need for hospitalization with the use of the 5-HT₃ receptor antagonist, ondansetron.

Freedman SB, Adler M, Seshadri R, Powell EC: Oral ondansetron for gastroenteritis in a pediatric emergency department. N Engl J Med 354:1698–1705, 2006.

Reeves JJ, Shannon MW, Fleisher GR: Ondansetron decreases vomiting associated with acute gastroenteritis: A randomized controlled trial. Pediatrics 109: e62, 2002.

Reid SR, Bonadio WA: Outpatient rapid intravenous rehydration to correct dehydration and resolve vomiting in children with acute gastroenteritis. Ann Emerg Med 28:318–323, 1996.

14 A 6-week-old infant presents with vomiting. What are the important historical findings that will help in distinguishing pyloric stenosis from gastroesophageal reflux?

The typical history of an infant with pyloric stenosis is that of nonbilious vomiting beginning around 2 weeks of age that worsens in force and volume over the next several weeks. As the degree of obstruction increases, the vomiting becomes projectile and typically occurs during or soon after feeding. Most commonly seen in first-born infants, pyloric stenosis affects males five times more often than females. By contrast, gastroesophageal reflux typically presents soon after birth and is characterized by effortless, nonprogressive spitting up, frequently occurring with burping or within 30–60 minutes after feeding. In most cases, the infant with gastroesophageal reflux will thrive despite the parent’s impression that “he’s been vomiting everything since birth.”

15 What are the important physical examination and laboratory findings that will help distinguish pyloric stenosis from gastroesophageal reflux?

If the vomiting has progressed significantly, the physical examination in an infant with pyloric stenosis may reveal a fussy, hungry infant who sucks vigorously unless weakened by dehydration. Peristaltic waves may be visible on inspection of the abdomen, and an olive-shaped mass (the hypertrophied pylorus) may be palpable in the subxiphoid region. The classic electrolyte abnormalities noted in pyloric stenosis are hypochloremia, hypokalemia, and metabolic alkalosis.

Papadakis K, Chen EA, Luks FI, et al: The changing presentation of pyloric stenosis. Am J Emerg Med 17:67–69, 1999.

16 A 12-month-old infant presents with vomiting and intermittent abdominal pain. How will you differentiate gastroenteritis from intussusception in this patient?

The classic patient with intussusception is between 3 months and 2 years of age and presents with the triad of episodic cramping abdominal pain, vomiting, and bloody (“currant jelly”) stools. The pain typically lasts 5–10 minutes and is associated with crouching or drawing legs up, after which the infant may appear well or be lethargic. A tender mass may be palpated in the right upper quadrant, and in 75% of patients the stool will be positive for occult blood or grossly bloody. Early intussusception may be confused with gastroenteritis, although the latter is most often characterized initially by vomiting that progresses to diarrhea, fever, and nonspecific abdominal pain or cramping pain with defecation.

Harrington L, Connolly B, Hu X, et al: Ultrasonographic and clinical predictors of intussusception. J Pediatr 132:836–839, 1998.

17 An 8-year-old boy presents with headache and vomiting. How will you distinguish vomiting caused by an intracranial mass lesion from that associated with migraine headaches?

After headache, vomiting is the second most commonly noted symptom in children with intracranial mass lesions. However, vomiting is not likely to be the only abnormality. In >90% of children with vomiting from an intracranial mass, other neurologic or ocular abnormalities will be present. Vomiting that accompanies brain tumors is commonly seen in the mornings, is usually effortless (although it may become projectile), and is not particularly associated with meals or abdominal pain. The vomiting may persist intermittently for weeks. Vomiting associated with migraine headaches is typically associated with infrequent, severe, diffuse headaches that resolve with sleep or when the cephalgia is treated.

Squires RH: Intracranial tumors. Vomiting as a presenting sign. A gastroenterologist’s perspective. Clin Pediatr (Phila) 28:351–354, 1989.