Cause:Genetic?; sex-linked?
Pathophys:Concentric muscular hypertrophy of pyloric smooth muscle, in which nitric oxide synthetase deficiency precipitates the disease (Nejm 1992;327:511)
2-5/1000 births; M:F 4:1; 5% of affected fathers’ offspring will have, 20% of affected mothers’ children will have.
Sx:Well and gaining weight for 1st 3-5 wk of life, then develop projectile vomiting without bile in it; appetite despite stomach distention
Si:“Olive” in right upper quadrant by palpation in 85-100% (Ped Clin N Am 1998;45:729), Na, K, Cl depletion
r/o annular pancreas (rx with duodenojejunostomy); duodenal atresia; Addisonian crisis due to congenital adrenal hypoplasia; antral diaphragm
Lab:
Chem:Lytes show hypochloremic, hypokalemic alkalosis
Xray:Ultrasound; UGIS only if mass not seen or felt, to confirm dx