Balls in stomach effects? Doctor or nurses help!

So when my fiance was a child, he was hit in the testicles so hard that his testicles went back up into his stomach. He had to get surgery to have them removed and put back into his sack. He's never been checked to see if he has issues but just assumed that he can't have kids. I feel like he wants to get checked but is scared that he actually isnt able to have kids. But any doctor's/nurses advice on whether they think he's able to have kids or not would be great. Btw this happened under the age of 10.