I don’t know how much this is reliable:
A varicocele is an enlarged (varicose) vein in the cord that connects to the testicle. Varicoceles are found in 15 - 20% of all men and in 25 - 40% of infertile men. When varicoceles occur in both testicles, they may contribute to hormone imbalances that cause erectile dysfunction.
You could do some search also. :)