How to recognise yolk sack infection?

[Mollysaskia]

So my chick finally hatched!

All seems healthy but I'm paranoid about yolk sac infection. What do I look out for? I'm a first time hatcher so worried about absolutely everything! Don't wanna lose him.

Any pointers?

 

[Wyorp Rock]

Hi @Mollysaskia Welcome To BYC
Hopefully others will chime in, but in the meantime, maybe this article will help you.
https://www.backyardchickens.com/articles/mushy-chick-disease-yolk-sack-infection-omphalitis.64686/