Narindra is a 4 week old infant who presents with vomiting. He has been thriving and breast feeding vigorously. Two days ago he started vomiting for the first time and then again yesterday with the observation “the vomiting spurted out everywhere like a hose. It was unbelievable.” Now he is vomiting after every feed and seems hungry. On examination he is a well nourished baby with no signs of dehydration.

Vital signs are:
Pulse 145
Respiration rate 48
Temperature 37 C.
No mass is palpable.
After test feeding there was a large forceful vomit of milk with distension of the upper abdomen and a peristaltic wave across the epigastrium.

Which of the following statements do you consider to be correct?