Thanks for those answers.
We've been told that it's unlikely to be pyloric stenisis due to her age and coz she's a girl. TBH I didn't realise where the pylorus was so thanks for the link Jenna.
I've just had a look at duodenal atresia but whatever my daughter has doesn't seem that exteme. She doesn't projectile vomit and is putting on a bit of weight.
It was the sonographer who mention the duodenum specifically I should have asked more questions but there wasn't much time.
Can a person have a mild form of either duodenal atresia or pyloric stenosis? which may explain why her symptoms are slightly less severe