DS just had his 3 year check up and his dr noticed a small hydrocele I think he called it on his one testicle... Anyone have any experience with this? It's the same dr we always see so he was surprised to find it this time as it's never been there before. He is doing a recheck in 3 months to see if it's still there/seems larger. If it is he mentioned seeing a specialist.

I've never heard of this before and thought I'd ask for anyone's experience or knowledge.