Do varicoceles ever cause male infertility?

Yes: Varicoceles are a common cause of decreased sperm count which can contribute to a couple's infertility. The dilation of veins around the testes can elevate the temperature and reduce the natural progression of sperm development. This is a very treatable condition and any one who suspects this is an issue should consult a urologist.

Yes but ...: Varicoceles may decrease sperm numbers and/or motility, or reduce sperm morphology (the percent of sperm with normal shape) by raising the temperature of the testicle(s). Large varicoceles or varicoceles on both sides may have more effect. In older men, they may cause reduced testosterone levels. Surgical removal rarely causes dramatic improvements in sperm numbers or quality, bur may help some.

Maybe.: There are many theories why varicocele may cause reduction in count, motility and normal shaped sperm. Although surgical repair of varcocele may improve sperm parameters there is no evidence that it increase the chance of pregnancy in female partners. The decision to repair varicocele to enhance fertility in men is not supported by strong scientific evidence.

Maybe rarely: I agree with prior answers and all too often seen worsening of the sperm parameters after repair.

Absolutely: Varicoceles can contribute to abnormalities in semen parameters as well as sperm dna fragmentation both of which can hinder ability to get partner pregnant. Best to see male infertility specialist for diagnosis and management.