MD Notes

creation date: 2026-09-21 18:34
tags: Workups

Nausea & Vomiting (Pediatrics)

Background

Nausea and vomiting is a common sequelae for many disorders that can range from self-limited illness to life-threatening conditions.

Vomiting (emesis) refers to forceful oral expulsion of gastric contents associated with coordinated contraction of abdominal and chest wall masculature.

Vomitus often has a slight yellow tinge caused by reflux of small amounts of bile into the stomach. Billous vomit is green or bright yellow colour and indicates large amounts of bile in the stomach.

Nausea refers to the sensation of unpleasantness that may precede vomiting. It is associated with autonomic changes such as salivation, increased heart rate, and increased respiratory rates.

Pathophysiology

Vomiting is thought to have a physiologic benefit as it is a mean to expel potential toxins. It also can induce a conditioned aversion to ingested toxins, further protecting an individual from future ingestions.

In disease states, however, vomiting pathways are inappropriately activated resulting in the act of vomiting.

The sequence of events that results in vomiting are:

  1. The diaphragm descends and the intercostal muscles contract while the glottis is closed
  2. The abdominal muscles contract and the gastric contents are forced into the gastric fundic area and lower esophagus
  3. Abdominal muscles relaxes and the esophageal refluxate empties back into stomach
  4. Several cycles of retching, each more rhythmical and forceful occur with shorter intervals in between
  5. Abdominal contraction with the elevation of the diaphragm results in forceful expulsion of gastric content

Differential Diagnosis

Predominantly Neonates & Young Infants

  • Pyloric stenosis (most common cause in infants)
  • Intestinal obstruction
    • Intestinal atresia
    • Intestinal volvulus
    • Hirschsprung disease
    • Intussusception
  • Inborn errors of metabolism
    • Organic acidemias
    • Urea cycle disorders
    • Galactosemia
    • Hereditary fructose intolerance
  • Immunologic reaction to food
    • Food protein-induced enterocolitis syndrome
    • IgE-mediated food allergy
  • Adrenal insufficiency

Many Age Groups

Infectious causes

  • Gastroenteritis (most common cause), typically viral
  • Pharyngitis, otitis media, UTI

Gastrointestinal obstruction

  • Intussusception
  • Malrotation

Other GI causes

  • GERD
  • Gastroparesis
  • Appendicitis
  • Eosinophilic esophagitis or gastroenteritis
  • Inflammatory bowel disease

Gut-brain interaction disorders (functional disorders)

  • Functional dyspepsia
  • Chronic nausea syndrome
  • Cyclic vomiting syndrome
  • Cannabis hyperemesis syndrome
  • Rumination syndrome

Endocrine/metabolic

Neurologic

  • Intracranial hypertension
  • Migraine

Others

  • Posttussive (consequence of vigourous or paroxysmal coughing, classically symptom of pertussis infection)
  • Food allergy
  • Pregnancy
  • Bulimia
  • Toxic ingestion
  • Medical child abuse (Munchausen syndrome by proxy)

Initial Evaluation

Red Flags

Concerning signs include:

  • Nonspecific
    • Prolonged vomiting
    • Profound lethargy
    • Significant weight loss
  • Gastrointestinal obstruction or disease
    • Bilious vomiting
    • Projectile vomiting in a young infant <12 weeks of age
    • Hematemesis
    • Hematochezia
    • Marked abdominal distension and tenderness
  • Neurologic or systemic disease
    • Bulging fontanelle in a neonate or young infant
    • Headache, positional triggers for vomiting, vomiting on awakening, and/or lack of nausea
    • Altered consciousness, seizures, or focal neurologic abnormalities
    • History of head trauma
    • Hypotension disproportionate to the apparent illness and/or hyponatremia and hyperkalemia

Signs should prompt specialist consultation depending on suspected cause.

History

History should include:

  • Onset and pattern of the vomiting and nausea (acute, chronic, episodic)
  • Associated symptoms
  • Recent exposures to contacts with similar symptoms
  • Possibility of ingestion of medications or toxic substances

The nature of vomiting can point to specific diagnoses:

  • Bilious - intestinal obstruction, especially in neonates
  • Projectile nonbilious vomiting - pyloric stenosis
  • Hematemesis - esophageal varices, Mallory-Weiss, mucosal injury from erosive
  • Acute, recent onset of vomiting, with diarrhea/fever - infectious gastroenteritis
  • Onset after infectious illness - postinfectious gastroparesis
  • Recurrent or periodic episodes of vomiting - inborn errors of metabolism, cyclic vomiting syndrome, cannabis hyperemesis syndrome
  • Early morning nausea and vomiting - pregnancy, increased ICP, cyclic vomiting syndrome
  • Prolonged vomiting (>12 hrs in neonate, >24 hrs in <2 years old, >48 hrs in older children) - obstruction, metabolic disorder, or cyclic vomiting syndrome
  • Lack of associated nausea and positional triggers - elevated ICP

Physical Exam

Physical exam should include:

  • Abdominal exam
  • Neurologic exam

Other findings include:

  • Atypical genitalia - possibility of adrenal insufficiency
  • Unusual odour - metabolic causes
  • Enlarged parotid glands - bulimia

Investigations

Laboratory investigations are indicated for vomiting that is severe and prolonged vomiting (>12 hrs in neonate, >24 hrs in <2 years old, >48 hrs in older children), or unexplained.

  • CBC
  • Electrolytes
  • Glucose
  • BUN
  • ALT, AST
  • Amylase, lipase
  • Urinalysis

For suspected intestinal obstruction:

  • Plain abdominal radiograph
  • Abdominal ultrasound (pyloric stenosis and intussusception)
  • Upper GI contrast study
  • Contrast enema

References

Tools / Guidelines

Additional Reading