Differentials
Gastroesophageal reflux
SIGNS / SYMPTOMS
Emesis similar to that in pyloric stenosis may occur after feeding but is not forceful, and it is usually small in volume and effortless. The emesis can rarely contain blood.
Gastroesophageal reflux can lead to failure to thrive, chronic lung disease, esophagitis, and esophageal strictures.[54] Symptoms usually begin by 6 weeks of life but resolve by 2 years of age.[55]
INVESTIGATIONS
Barium swallow and radionuclide scan may show esophageal reflux, and endoscopy may show superficial esophageal ulcerations or inflamed mucosa.[54] Overnight esophageal pH monitoring showing low pH is the diagnostic standard.
Electrolytes are usually normal, although chloride may be slightly depressed due to emesis.[56]
Overfeeding
SIGNS / SYMPTOMS
Infants will not have difficulty gaining weight.
INVESTIGATIONS
Can be determined by estimating appropriate feeding volumes and comparing them with actual volumes.
Chemistry panel and ultrasonographic measurements of pyloric muscle thickness and channel length will be normal.
Malrotation
SIGNS / SYMPTOMS
Many cases present in adulthood.[57]
The key symptom is bilious emesis, unlike nonbilious emesis seen in pyloric stenosis.
INVESTIGATIONS
Upper GI fluoroscopic contrast study will show duodenojejunal junction not crossing midline. If the midgut is volvulized around its mesentery, the classic corkscrew appearance of contrast flowing to the jejunum will be seen.[57]
Acute infectious diarrhea
SIGNS / SYMPTOMS
Diarrhea generally follows vomiting. Diarrhea is seldom seen in pyloric stenosis, which usually presents with constipation.
INVESTIGATIONS
Infants with infectious diarrhea can have severe volume depletion and electrolyte disturbances similar to those seen in pyloric stenosis.
Stool cultures may show Escherichia coli, Campylobacter jejuni, Salmonella, or Shigella.
Food allergy
SIGNS / SYMPTOMS
Clinical features are vomiting and diarrhea for the first 3 months of life.
Bloody diarrhea can be seen due to the development of allergic colitis.
INVESTIGATIONS
In addition to dietary history, diagnosis is based on exclusion of allergic agents.
Antral web
SIGNS / SYMPTOMS
Typically, diagnosed after a long period of symptoms. Diagnosis can occur up to 5 years of age.
INVESTIGATIONS
Barium upper GI imaging is diagnostic in 90% of patients, showing double bulb (normal duodenal bulb and proximal antral chamber between the web and the pylorus).[58]
Duodenal atresia
SIGNS / SYMPTOMS
Seen in neonates.
Bilious emesis is seen in 85% of patients, as most atresias are distal to the ampulla of Vater.[57] Patients with pyloric stenosis present with nonbilious projectile emesis.
One third of infants with duodenal atresia have Down syndrome.[59]
INVESTIGATIONS
Prenatal ultrasound may show polyhydramnios and fluid-filled stomach and proximal duodenum.
Classic sign is a double bubble on an abdominal radiograph.[57]
Jejunoileal atresia
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