Pyloric Stenosis



Acquired narrowing of the pyloric canal due to progressive hypertrophy of pyloric muscle leading to obstruction


  • Presentation is most common between 2 and 8 weeks of age, with a median presentation of 6 weeks
  • The most common condition requiring surgical intervention in the 1st year of life


  • Highest incidence found in first-born males
  • Overall 1.56 per 1,000 live births
  • Higher in Caucasian and Hispanic children

Etiology and Pathophysiology

  • Impaired physiologic relaxation of the pyloric muscle leads to hypertrophy.
  • Gastric outflow is obstructed, leading to gastric distension and forceful projectile postprandial vomiting.

Risk Factors

  • Maternal smoking during pregnancy
  • C-section delivery
  • Prematurity
  • Formula feeding which may cause higher serum levels associated with pylorospasm
  • Postnatal macrolide antibiotics, especially if administered in the first 2 weeks of life
  • Multiple gestations:
    • 200-fold increased risk if monozygotic twin affected
    • 20-fold increased risk if dizygotic twin affected

General Prevention

Breast milk contains increased vasoactive intestinal peptides which are agents of smooth muscle relaxation.

Commonly Associated Conditions

Hiatal and inguinal hernias

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