What is true regarding congenital hyperophic pyloric stenosis

Congenital hyperophic pyloric stenosis is more common in first born males.Symptoms usually sta after 3 weeks of age.Non-bilious vomiting is the initial symptom. After vomiting, the infant becomes hungry and wants to feed again.The metabolic disturbance is hypochloremic metabolic alkalosis.Clinical diagnosis is by palpation of hyperophic mass, confirmed by USG.The surgical procedure of choice is Ramstedt pylorotomy.Ref: Nelson 17th/e p1229