Symptom-Based Diagnosis in Pediatrics (CHOP Morning Report) 1st Ed.

CHAPTER 3. VOMITING

PAUL L. ARONSON

DEFINITION OF THE COMPLAINT

Vomiting is defined as the forceful contraction of abdominal muscles and the diaphragm in a coordinated fashion expelling the gastric contents through an open gastric cardia into the esophagus and out through the mouth. The medullary vomiting center coordinates this process of vomiting via efferent pathways of the vagus and phrenic nerves. Stimulation of the medullary vomiting center occurs either directly or through the chemoreceptor trigger zone. Direct stimulation may occur through afferent vagal signals from the gastrointestinal tract or other sites including but not limited to the vestibular system, the cerebral cortex, or the hypothalamus. The chemoreceptor trigger zone in the area postrema of the fourth ventricle can be activated by noxious sights and smells or by chemical stimuli in the blood secondary to medications, metabolic abnormalities, and certain toxins.

Gastroesophageal reflux is not vomiting but rather regurgitation, and despite being projectile at times, is an effortless return of gastric contents into the mouth without nausea or coordinated muscular contractions.

COMPLAINTS BY CAUSE AND FREQUENCY

It is important to remember that vomiting is not a diagnosis but rather a symptom of an underlying pathologic process that requires a thorough evaluation. The causes of vomiting can be grouped based on age of presentation (Table 3-1) or etiology (Table 3-2).

TABLE 3-1. Causes of vomiting and regurgitation in childhood by age.

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TABLE 3-2. Causes of vomiting and regurgitation in childhood by etiology.

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QUESTIONS TO ASK AND WHY

Thorough history taking is imperative for formulating an accurate differential diagnosis and eventually discovering the correct etiology of vomiting. Consideration of the vomiting duration and pattern, the content of the emesis and associated symptoms provides a framework for creating a differential diagnosis. The following questions may help provide clues to the correct diagnosis:

• What is the duration of vomiting?

—Acute episodes of vomiting carry a much different differential diagnosis than either chronic or cyclic vomiting. Acute vomiting is mostly due to infectious or metabolic conditions though it may also be caused by toxic ingestions or surgical emergencies, such as appendicitis and ovarian torsion. Chronic vomiting tends to have a gastrointestinal etiology and may be due to a partial mechanical obstruction as seen in hiatal hernia, or chronic gastrointestinal diseases, such as inflammatory bowel disease or celiac disease. Other conditions causing prolonged vomiting include peptic ulcers, dysmotility syndromes, increased intracranial pressure, psychogenic disturbance, pregnancy, and lead poisoning. Cyclic vomiting tends to be extraintestinal and is usually due to migraine or migraine equivalents, cardiac arrhythmias, or ureteral pelvic junction (UPJ) obstruction. Inborn errors of metabolism, while rare, are another cause of cyclic vomiting especially if associated with episodic neurologic symptoms.

• Is there any timing pattern to the vomiting?

—Episodes of vomiting that occur with a regular diurnal pattern are also helpful clues. Early morning vomiting can be very ominous due to increased intracranial pressure but could also occur secondary to morning sickness from pregnancy. Vomiting after eating specific foods may be due to a food allergy. Vomiting patterns may also become apparent if secondary gain is achieved, such as absence from school or tests, or it may be associated with school phobia. Vomiting that occurs shortly after eating is consistent with esophageal or gastric outlet obstructions or peptic ulcer disease, though may also be due to psychogenic vomiting.

• Is the vomiting effortless?

—Gastroesophageal reflux occurs in almost all newborns, but by 6 months of age, less than 5% of children are symptomatic. It tends to be effortless, not associated with pain or morbidity. Rarely will reflux be severe enough to cause discomfort and arching, Sandifer syndrome (in which the reflux mimics seizure activity), or poor weight gain at which point medical therapy may be necessary. True vomiting tends to be a more noxious event often causing pain and retching.

• Is there bilious emesis?

—The presence of bilious emesis suggests an obstruction distal to the ampulla of Vater but may also be present in nonobstructed patients after prolonged episodes of vomiting due to a relaxed pylorus. Bilious vomiting in a neonate should be treated as a surgical emergency until proven otherwise. Neonates with bilious emesis may have intestinal obstruction associated with malrotation and midgut volvulus or less commonly, intestinal atresias. The absence of bilious emesis is also important, especially in neonates, because obstruction proximal to the ampulla ofVater (e.g., pyloric stenosis) may cause frequent nonbilious emesis.

• Is there any blood in the vomitus?

—Either a Gastroccult or Hematest must first confirm the presence of blood in emesis. If blood is present then hematemesis must be distinguished from hemoptysis. The blood in hematemesis ranges from bright red to coffee-ground depending on its length of time in contact with gastric contents, but tends to be darker red in color, acidic and associated with retching or gastrointestinal complaints. The blood in hemoptysis is bright red, frothy, alkaline, and associated with respiratory symptoms. Hematemesis may be due to peptic ulcers, Mallory-Weiss tears, esophagitis, esophageal varices, acute iron ingestion, gastritis, vascular malformations, or bleeding diatheses.

• Is undigested food present in the vomitus?

—The presence of undigested food material is very common in children with gastroesophageal reflux who present with episodes of effortless postprandial regurgitation. Other conditions that predispose to undigested food in emesis include esophageal atresia or strictures, esophageal or pharyngeal (Zenker’s) diverticulum, or achalasia. Old food present in the emesis may signify a gastric outlet obstruction or a gastric motility disorder.

• Is fecal material present in the emesis?

—The presence of fecal material in the emesis is uncommon but when present suggests a distal intestinal obstruction such as Hirshsprung disease, peritonitis, gastrocolic fistula, or bacterial overgrowth in the stomach or small intestine.

• Is diarrhea occurring with the vomiting?

—The presence of diarrhea and vomiting suggests a gastrointestinal disorder of which an infectious gastroenteritis is the most common, though if chronic in nature can be due to inflammatory bowel disease or celiac disease. Isolated vomiting tends to have a far greater differential involving many other organ systems. Isolated vomiting may occur in serious conditions, such as increased intracranial pressure, lower lobe pneumonia, intentional or unintentional medication or toxin ingestions, and diabetic ketoacidosis.

•Is there any abdominal pain?

—When vomiting is accompanied by abdominal pain, the location of the abdominal pain, as well as the descriptive nature of the pain, can be clues as to the etiology. Pain in the right lower quadrant may be due to an acute appendicitis, whereas right upper quadrant pain is more likely to be gall bladder or hepatic in origin. Lower quadrant pain may also occur with ovarian torsion or pelvic inflammatory disease. The most common cause of diffuse abdominal pain with vomiting is gastroenteritis. Colicky pain tends to occur with an obstructed hollow viscous or urinary calculi, whereas well-localized sharp pain tends to occur when parietal peritoneum is inflamed. Flank or lateral pain signifies a renal etiology. Pain from peptic ulcer disease is often alleviated with vomiting, whereas pain secondary to pancreatitis or biliary tract disease is not improved with vomiting.

• Is fever present?

—The presence of fever in a patient with vomiting is common. It may signify an infectious gastrointestinal process, such as acute viral gastroenteritis, bacterial enteritis, appendicitis, hepatitis, pancreatitis, peritonitis, or an acute extraintestinal infection, such as sepsis, meningitis, acute otitis media, pharyngitis, or urinary tract infections. Other causes of fever include inflammatory conditions, such as inflammatory bowel disease.

• Are there any other associated symptoms present?

—Other information that may help in narrowing the differential includes the presence of weight loss, headache, lethargy, and poor school performance, as well as environmental and infectious exposures.

The following cases present less common causes of vomiting in children.