• 1/800 live births; 80% pts are male; often firstborn
  • Usually follows uncomplicated pregnancy
  • Etiology likely in part genetic (incidence is high monozygotic twins if the other twin has it; JAMA 303:2393, 2010-JW)
  • Uncommon in premature infants
  • Course is variable, depending on degree of stenotic obstruction
    1. 2-3 wks nl development, then progressive development of projectile vomiting--USUALLY NOT BILE-STAINED
    2. Weight loss, dehydration, constipation
  • Physical exam: corresponding to above, plus abd. distention, visible peristalsis, RUQ "olive"
  • Dx: UGI barium study "string sign"
  • Treatment:
  • Ramstead operation (pyloric myotomy)
  • NOTE--Erythromycin systemically administered in kids < 3mo was ass'd with RR 13.0 for pyloric stenosis in one retrospective study; no increase in risk with use of erythromycin ophthalmic ointment (J. Peds. 139:380, 2001--JW); in another population-based study, erythromycin use in kids < 14do was ass'd with RR 8.0 for pyloric stenosis; administration later was NOT found to be ass'd (Arch. Ped. Adol. Med. 156:647, 2002--JW)