Abdominal pain

A 14 month old infant attends ED with episodes of screaming and looking pale. His parents think his ‘stomach is hurting.’ He has vomited up his milk twice. He hasn’t opened his bowels today. On assessment, he looks pale and lethargic. HR 150, RR 35, CR 3 seconds, temperature 36.7^oC. Abdomen seems full in his right upper quadrant. Which investigation is most likely to be diagnostic?

A 3 month old girl attends ED with a 6 week history of vomiting after feeds. They are milky and seem effortless. She cries with them and seems unsettled. She is growing well along the 25^th centile. She has no other medical problems, and clinical examination is normal. What is the most likely diagnosis?

A 7 year old girl attends ED with abdominal pain. The pain has been going on for 6 months. She normally feels it around her belly button. On a few occasions, she has come home early from school because of it. She is growing well, and has a good appetite. Which of the following are red flags suggesting she needs further investigation?