Pyloric Stenosis



  • Postnatal hypertrophy and hyperplasia of the circular smooth muscle cell layer causing a thickened pylorus and antrum leading to progressive gastric outlet obstruction
  • Neuronal nitric oxide synthase (NOS-1) may be a genetic susceptibility locus
  • Administration of erythromycin and azithromycin in infants during first 2 wk of life may increase risk of hypertrophic pyloric stenosis
  • Jaundice due to transient glucuronyltransferase deficiency
  • Adult: Caused by peptic ulcer disease


  • Most common cause of GI obstruction in infants; incidence 1/150 males, 1/750 females (average: 3/1,000 live births)
  • Males affected 5× more commonly than females; firstborn most common
  • Familial aggregation noted, 15%:
    • Child of affected parent has 7% incidence
    • Recurrence risk in subsequent male children is 10%; 2% in females

There's more to see -- the rest of this topic is available only to subscribers.