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projectile. Emesis tends to worsen in frequency and severity over days to weeks.
In the past, diagnosis was made by clinical history and palpation of the
hypertrophied pyloric muscle, or “olive” in the abdomen. Infants often presented
with dehydration and electrolyte abnormalities caused by repeated vomiting,
typically a hypokalemic, hypochloremic metabolic alkalosis. However, with
earlier presentation and diagnosis, fewer patients have an olive palpated at
diagnosis, and the majority do not have the classic electrolyte derangements at
presentation. HPS is associated with erythromycin use in the first two weeks of
life; however, no association has been found between macrolide use during
pregnancy or breastfeeding and HPS.
HPS should be suspected in the young infant presenting with progressively
worsening nonbilious emesis, and can be diagnosed using ultrasound. A
hypertrophied pylorus with muscle wall thickness of 4 mm or greater and length
of 15 mm or greater with no passage of gastric contents into the small intestine
confirms the diagnosis. Treatment is surgical, with laparoscopic pyloromyotomy.
Prior to surgery, the patient should be well hydrated and any electrolyte
abnormalities should be corrected.
Intussusception occurs when one portion of the bowel telescopes into its distal
segment, commonly the terminal ileum into the cecum. The peak incidence for
intussusception is between 3 months and 3 years of age, although it remains one
of the most common causes of obstruction up to 6 years of age. Patients typically
present with intermittent episodes of abdominal pain, during which they may cry
or pull up the legs. Children may be lethargic between episodes, and infants may
present only with lethargy and without the classic episodes of pain. Bilious
emesis and blood-tinged “currant jelly” stools may be seen. However, the classic
triad of abdominal pain, vomiting, and bloody stools is seen in less than a quarter
of children with intussusception, so a high level of clinical suspicion must be
maintained when any of these symptoms are present (refer Chapter 53 Pain:
Abdomen ).
Less common causes of obstruction should also be considered in infants
presenting to the ED with vomiting. A thorough clinical examination should be

performed to evaluate for signs of incarcerated inguinal or umbilical hernias.
Meckel diverticulum, which results from incomplete obliteration of the
omphalomesenteric duct, is the most common congenital anomaly of the GI tract
in children. While the majority of patients are asymptomatic, children can
occasionally present with obstruction. Enteric duplication cysts can also lead to
intestinal obstruction or can act as lead points for intussusception.


While the clinician must first rule out obstructive causes of vomiting in infants,
nonobstructive causes are more common than obstructive causes. Nonobstructive
causes of vomiting in this age group include GI, infectious, neurologic, renal, and
metabolic disorders.
GER is a common cause of emesis in this age group. GER results when
relaxation of the LES allows retrograde passage of gastric contents. Infants with
GER may present with repeated episodes of emesis of stomach contents usually
within 30 minutes of feeding. Emesis is generally nonbloody and nonbilious, and
is fairly constant over time. Most infants will have some degree of GER or
“spitting up,” with a peak at age 4 months (up to 67% of infants) and gradually
tapering over the first year of life. GER that causes troublesome symptoms for the
patient is referred to as gastroesophageal reflux disease (GERD). Troublesome
symptoms that suggest GERD include poor weight gain, vomiting associated with
irritability or refusal to feed, arching of the back during feeding, and respiratory
symptoms such as cough or wheezing related to reflux. For infants who present
with reflux but without any of these troublesome symptoms, there is generally no
need for any further diagnostic testing or for medical management.
Nonpharmacologic treatments suffice for the vast majority of infants with reflux.
Upper GI contrast radiography and esophageal pH probes are the most commonly
used tests in the diagnosis and evaluation of GERD, but are almost never
indicated in the PED for reflux evaluation.
Management of both GER and GERD should include lifestyle modifications.

These modifications can include feeding changes such as avoiding overfeeding,
thickening feeds, and continuation of breastfeeding. As milk–protein allergy can
mimic GERD, a trial of eliminating milk and eggs from the diet of mothers of
breast-fed infants or a trial of hydrolyzed protein formula in formula-fed infants
may be warranted. Medications should be reserved for infants with continued
worrisome symptoms of GERD after trials of feeding modifications, with the two
classes of medications most commonly used in infants being histamine-2 receptor
antagonists (H2RAs) and proton pump inhibitors (PPIs). Medications should be
given a 2- to 4-week trial, with weaning if symptoms improve. It is important to
stress to parents that these medications will reduce acid exposure in children with
GERD, but that they will not decrease the amount of reflux itself. There has been
a shift away from acid-suppression therapy because of lack of efficacy and
possible adverse effects.
Viral gastroenteritis is another common cause of vomiting in infants. The infant
will generally present with diarrhea as well, although they may present without
diarrhea or early in the disease course before diarrhea has developed. It is crucial


to assess hydration of infants presenting with gastroenteritis and to ensure
adequate oral intake, particularly in those infants who also have diarrhea as this
age group is at much higher risk of dehydration than older children.
Vomiting in infants may also be caused by pathology of organ systems outside
the digestive system and should be considered in the infant presenting with
vomiting. These include infectious, neurologic, renal, and metabolic causes.
Infections outside the GI tract can present with vomiting in infants. One of the
most common infections to cause vomiting outside of the GI tract is UTI. UTIs
are a common source of fever in children, particularly in infants. Clinical
symptoms are often nonspecific in infants, but may include vomiting in as many
as one-third of infants with UTI, poor feeding, or malodorous urine. Infants with
pneumonia may also present with fever and vomiting, along with tachypnea,

cough, or increased work of breathing. Any respiratory illness causing cough,
including bronchiolitis, pneumonia, and pertussis, can be associated with
posttussive emesis in this age group.
Neurologic causes of vomiting in infants include CNS infections such as
meningitis, hydrocephalus, intracranial mass, and intracranial hemorrhage. Signs
and symptoms of increased ICP in infants may include vomiting in addition to
lethargy, irritability, bulging anterior fontanel, seizures, or focal neurologic
findings.
Other causes of vomiting outside the GI tract include renal and metabolic
causes. Infants with renal tubular acidosis (RTA) may present with vomiting,
growth failure, and recurrent episodes of dehydration. Children with renal failure
may also present with vomiting. Vomiting can be an early symptom of many of
the inborn errors of metabolism, including urea cycle disorders and organic
acidemias. Infants with inborn errors of metabolism may present with vomiting,
lethargy, and poor feeding, and this diagnosis should be kept in the differential
diagnosis of infants presenting with recurrent vomiting.

Older Child
In the older child, several of the obstructive causes of vomiting can continue to
occur, although less commonly than in infancy. Children in this age group may
present with malrotation and volvulus, intussusception, incarcerated hernia, or
enteric duplication cysts. Children with a history of abdominal surgery may
present with bowel obstruction caused by adhesions. Signs of obstruction in this
age group include vomiting (particularly bilious), abdominal distention, and pain.
Nonobstructive causes of vomiting continue to be more common than
obstructive causes of vomiting in older children. GI causes such as appendicitis,
peptic ulcer disease, and gastroenteritis can lead to vomiting, as well as several


extra-abdominal causes. Appendicitis can present with vomiting in children,

along with other symptoms including abdominal pain, anorexia, and fever. Often,
pain will begin in the periumbilical region and then shift to the right lower
quadrant, and pain may be increased with coughing or hopping (Chapters 53
Pain: Abdomen and 116 Abdominal Emergencies ).
Other nonobstructive causes of vomiting in older children related to the
digestive system include pancreatitis, cholelithiasis and cholecystitis, gastritis,
and peptic ulcer disease. Children with pancreatitis may present with vomiting
and severe pain and tenderness in the epigastric region. Children with
cholelithiasis may present with vomiting and pain in the right upper quadrant,
with symptoms worsening particularly after eating fatty foods, while those with
cholecystitis may present with similar symptoms with the addition of fever. Peptic
ulcer disease may also present with vomiting, as well as abdominal pain worst in
the epigastric region and hematemesis in severe cases.
Acute gastroenteritis (AGE) is the most common cause of vomiting in this age
group. AGE is an infection characterized by diarrhea, often accompanied by
vomiting and is a common reason for children to present to the ED. Fever may or
may not be present. The degree of dehydration will help to determine how to
manage the child. Several scales exist to assess the severity of dehydration (mild,
moderate, or severe) in children with AGE based on physical examination,
including criteria from the World Health Organization (WHO), the Gorelick
scale, and the Clinical Dehydration Scale (CDS). These scales may have limited
utility in some settings, and percentage loss of weight, although not often readily
available in the ED, is the gold standard for assessing degree of dehydration.
Laboratory studies may also be helpful in children with signs of severe
dehydration, with serum bicarbonate level having been shown to correlate with
dehydration in several studies, but are rarely indicated in children with mild or
moderate dehydration (see Chapter 22 Dehydration ). Intravenous fluids are
generally recommended for the treatment of severe dehydration, and admission to
the hospital may be indicated in these children, particularly if ongoing losses
exceed intake. However, oral rehydration should be attempted prior to

intravenous rehydration in children with mild or moderate dehydration.
Ondansetron may be helpful in children prior to attempting oral rehydration in
vomiting patients. It is important that parents realize that rehydration in the ED is
only the first phase of treatment of dehydration, with the second and third phases
being replacement of ongoing losses and continuation of normal feeding.
Education on how to replace ongoing fluid losses after discharge from the ED
should be provided. Symptoms will generally improve over a few days to a week.