Review Question - QID 107551

This patient's presentation is consistent with hypertrophic pyloric stenosis. Hypertrophic pyloric stenosis occurs secondary to thickening of the pylorus muscle with resultant gastric outlet obstruction.

Hypertrophic pyloric stenosis typically presents between 4-6 weeks of life and is more common in first-born male patients. Symptoms include a palpable, movable mass in the right side of the epigastrium, non-bilious vomiting after most or every feeding, weight loss, failure to thrive, and abdominal pain. Patients may present with dehydration and electrolyte imbalances if left untreated.

Taylor et al. provide an updated overview of infantile hypertrophic pyloric stenosis. The authors found that in their population, patients are being diagnosed earlier with less electrolyte abnormalities due to more aggressive use of ultrasound, the gold-standard diagnostic study. The most common presentations were: non-bilious vomiting, palpable olive shaped mass, failure to thrive, dehydration and visible peristalsis.

Maheshwai reviews the relationship of oral erythromycin and hypertrophic pyloric stenosis. They found that infants who are exposed to oral erythromycin within the first two weeks of life have a significantly increased risk of developing hypertrophic pyloric stenosis. This relationship is hypothesized to be related to the action of erythromycin on motilin receptors in the pylorus.

Incorrect Answers:
Answer 1: Gastroesophageal reflux in infants presents with spitting and emesis after feeding without any other pathology.
Answer 3: Milk-protein allergy may present with vomiting, blood in stool, or anemia.
Answer 4: Midgut volvulus presents with bilious vomiting and sudden acute abdominal pain.
Answer 5: Instussusception presents with vomiting, intermittent acute abdominal pain, and bloody stool typically between 5-9 months of age. A right upper quadrant mass is sometimes palpated.