Your doctor may refer you to a specialist and do further tests including: blood tests, a barium meal-your baby swallows a drink containing barium(a substance that shows up on X-rays), X-ray images of the tummy that show the inside of his/her bowel more clearly, an ultrasound scan-this uses sound waves to produce an image of the inside of the abdomen and will show the thickened pylorus muscle.
Attribution: BUPA