29th September 2021

A 7 week old male infant is brought to A&E by his parents as today he has been vomiting forcefully

A 7 week old male infant is brought to A&E by his parents as today he has been vomiting forcefully after each feed. He has been vomiting up feeds since yesterday but today’s vomiting has been more forceful and concerning. He has had fewer wet nappies than usual and has been very irritable. A blood test on admission shows hypochloraemic hypokalaemic alkalosis, suggestive of persistent vomiting.

Which of the following is the most appropriate investigation to diagnose this infant’s condition?

Select the SINGLE most appropriate option from the list below. Select ONE option only.