What causes enlarged blood vessels in male testicle?

Varicocele: Failure of the valves in the spermatic vein (most common on the left) can lead to varicosities of the scrotum known as a 'varicocele.' this is sometimes described as making the scrotum look like a "bag of worms." if there is no pain and no fertility issue, no treatment may be necessary. Varicoceles are treated when they cause pain or if there is subfertility.