Review Question - QID 107693

The patient’s postprandial non-bilious vomiting, persistent appetite, and “olive-like” mass is highly suggestive of pyloric stenosis (PS).

PS is due to hypertrophy of the pylorus muscle, which is located at the junction between the stomach and the duodenum. This hypertrophy narrows the antrum of the stomach, leading to vomit that is non-bilious. Vomiting leads to a hypochloremic, hypokalemic metabolic alkalosis. Alkalosis is due to the loss of hydrogen in the vomit, and aldosterone production secondary to hypovolemia increases renal potassium excretion. There is paradoxical aciduria due to renal sodium conservation with secondary hydrogen ion loss due to an ion exchange mechanism. The etiology of PS may have a genetic and environmental component. This condition is more common in boys, with symptoms appearing around 3-to-5 weeks of life. Pyloromyotomy is considered definitive treatment of PS.

Aspelund et al. present a review article on PS management. Surgical intervention should be deferred until there is appropriate fluid and electrolyte resuscitation of the infant. There is an associated low incidence of morbidity and mortality with pyloromyotomy.

Eberly et al. explored the association of azithromycin use in infants and PS. Young infant exposure to azithromycin and erythromycin in the first 2 weeks of life has a strong association with infantile hypertrophic PS.

Incorrect Answers:
Answer 1: Intussusception is classically characterized by abdominal pain, a palpable right quadrant sausage-shaped mass on the abdomen, and currant-jelly stools. These patients may present with non-bilious vomiting initially, but as the obstruction gets worse, there is bilious vomiting.
Answer 2: Duodenal atresia may be due to a recanalization error during development. This condition has an association with Trisomy 21 (Down syndrome). These patients would present with bilious vomiting within hours of birth.
Answer 4: Aganglionic colon segment describes Hirschsprung disease. There is also an association with Down syndrome. These infants fail to pass meconium, and have bilious vomiting. This disease may be due to a neuroblast caudal migration defect.
Answer 5: Achalasia is due to failure of the lower esophageal sphincter to relax. This rarely occurs before adolescence. Achalasia patients have dysphagia to both solids and liquids. Our patient’s clinical presentation is not consistent with Achalasia.