Vasectomy is a procedure used for sterilization that entails removing a small section of the vas deferens (the tube that carries sperm from the testicle to the urethra, during ejaculation). This is a technical surgery that requires accurate knowledge of the anatomy of the spermatic cord and meticulous attention to detail. If the wrong tissue is removed or too small a portion is removed, fertility may remain or may return at some time after surgery. After vasectomy is performed, testosterone levels will remain the same, along with all other male traits (drive, interest in breeding, male behaviors).