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Does Varicocele Affect Sperm?

Q: I am a 31 year old male. I want to know if varicocele affects sperm?

A: A varicocele may affect fertility.  About 10% of men have a left sided varicocoele due, in part, to the anatomical effect of the compression of the left renal vein between the superior mesenteric artery and the aorta (the “nutcracker effect”) increasing the venous pressure in the left gonadal vein.  This pressure leads to varicose veins in and around the testicle.  The scrotum is a cooling device for the testicles, resulting in a drop of 1-2 degrees below body temperature.  The varicocoele may interfere with the cooling of the testicles, and thus impair fertility.  The reasons behind the varicocele/fertility question are more complex, and not fully understood as of yet.  While many men have a varicocele, most are not infertile.  Yet correcting a varicocele for a man with infertility results in pregnancy in about 50% of cases.