What are the causes of a hernia in the testicles?

Inguinal hernia. Inguinal hernia is 4 types. Testicular hernia or indirect inguinal hernia is congenital or you are born with. This is what we call patent processus vaginalis. As we grow older the patent tract get bigger thus leading to the hernia.
Large enough. If an inguinal or groin hernia becomes large enough, then the hernia contents or intestines can fall into the scrotum near the testicle. This will result in visible swelling in the testicle region.