Mild bilateral varicocele does this need an operation to be done or no and does this affect fertility?

Yes and no: While 40% of "infertile" men have at least a one-sided varicocele, 10% (1/10) of all men have a unilateral varicocele, and 1% (1/100) have bilateral varicoceles; and yet, we don't see as many with c/o infertility. Prudent to treat if they are causing pain, testicular atrophy, semen abnormalities or severe cosmetic reasons (deformity). There is no medical management: either embolization or ligation.