The most common side effects after a vasectomy are mild pain, bruising, bleeding, and swelling. Of course it is still possible for more severe issues to occur, though they are incredibly rare. These include: Infection Chronic pain Failure to prevent pregnancy Granuloma (inflammation caused by leaking sperm) Spermatocele formation (a small cyst of the upper testicle region) Hydrocele (a fluid-filled sac of tissue that grows within the scrotum) Individuals at risk for more serious complications include those who have suffered testicular cancer or testicular disease, though even in these outlying groups rarely encounter serious side effects caused by a vasectomy. Be sure to discuss your own individual risk factors with your urologist to determine if a vasectomy is a safe option for you.