A three week old infant presented in the paediatric outpatient department having non bilious vomiting; which is projectile in nature. O/E child is found to be slightly dehydrated. A vigorous peristaltic wave was seen to move from left hypochondrium to umbilicus after feeding. The most likely diagnosis in the infant is:

Ans. A. Pyloric stenosisThis is a classical presentation of Idiopathic HPS. It is the most common surgical disorder of gastrointestinal tract in infants.This disorder is 4-6 times more common in boys than girls. In 75-80% of affected infants, a firm olive shaped mass is palpable in the medgastrium. USG abdomen is the diagnostic investigation and shows muscle thickness of >4mm & pylorus length>16mm.