To diagnose pyloric stenosis, your doctor will ask about your baby's symptoms and examine him/her feeling for a small hard lump on the right-hand side of the stomach. It's called the 'olive test' because the thickened pylorus feels like an olive. It's especially noticeable when your baby is feeding so your doctor may ask you to give the baby a feed and examine your baby during this and any vomiting that occurs afterwards. During the feed, she/he will check if the muscles around baby's stomach are moving from side to side as they try to push milk through the pylorus. She/he will also want to rule out other conditions that can cause these symptoms e. g. infection, overfeeding or a milk allergy.
Attribution: BUPA