Vasectomy is a surgical procedure for male sterilization and/or permanent contraception. During the procedure, the male vas deferens are severed and then tied/sealed in a manner so as to prevent sperm from entering into the seminal stream (ejaculate) and thereby prevent fertilization. Vasectomies are usually performed in a physician's office, medical clinic, or, when performed on an animal, in a veterinary clinic— hospitalization is not normally required as the procedure is not complicated, the incisions small, and the necessary equipment routine.