FCEM2-1442

A 6 week old female is brought into the emergency department by concerned new parents. They inform you that for the past couple of days, the baby has been vomiting forcefully after each feeding and is not urinating as frequently as usual. The parents are anxious as the baby was delivered via C-section at full term and is solely bottle fed. During the examination, you detect a lump in the upper abdomen.

What is the most probable diagnosis?